diff --git a/docs/design-principles/0150-all-use-cases.md b/docs/design-principles/0150-all-use-cases.md
index 77a5f7ec..c1bebf65 100644
--- a/docs/design-principles/0150-all-use-cases.md
+++ b/docs/design-principles/0150-all-use-cases.md
@@ -80,12 +80,12 @@ These are the main use cases of this product that are exposed via "public" APIs
 
 #### Machines
 
-1. Register a new machine
+1. Register a new machine (anonymously or by authenticated user)
 
 #### Password Credentials
 
 1. Authenticate the current user (with a password)
-2. Register a new person (with a password, and optional invitation)
+2. Register a new person (with a password and with optional invitation)
 3. Confirm registration of a person (from email)
 
 #### Single-Sign On
@@ -98,9 +98,9 @@ TBD
 
 ### Organizations
 
-1. Create a new organization for the current user
+1. Create a new (shared) organization for the current user
 2. Inspect a specific organization
-3. Invite another user to the organization (by email, or an existing user by email or by ID)
+3. Invite another guest or person to an organization (guest by email, or an existing person by email or by ID)
 
 ### Subscriptions
 
diff --git a/src/Application.Resources.Shared/EndUser.cs b/src/Application.Resources.Shared/EndUser.cs
index 82b43fee..bd52f492 100644
--- a/src/Application.Resources.Shared/EndUser.cs
+++ b/src/Application.Resources.Shared/EndUser.cs
@@ -56,6 +56,15 @@ public class Membership : IIdentifiableResource
     public List<string> Roles { get; set; } = new();
 
     public required string Id { get; set; }
+
+    public required string UserId { get; set; }
+}
+
+public class MembershipWithUserProfile : Membership
+{
+    public EndUserStatus Status { get; set; }
+
+    public required UserProfile Profile { get; set; }
 }
 
 public class Invitation
diff --git a/src/Application.Resources.Shared/Organization.cs b/src/Application.Resources.Shared/Organization.cs
index 63dde585..7a40e8d3 100644
--- a/src/Application.Resources.Shared/Organization.cs
+++ b/src/Application.Resources.Shared/Organization.cs
@@ -24,4 +24,27 @@ public enum OrganizationOwnership
 {
     Shared = 0,
     Personal = 1
+}
+
+public class OrganizationMember : IIdentifiableResource
+{
+    public UserProfileClassification Classification { get; set; }
+
+    public string? EmailAddress { get; set; }
+
+    public List<string> Features { get; set; } = new();
+
+    public bool IsDefault { get; set; }
+
+    public bool IsOwner { get; set; }
+
+    public bool IsRegistered { get; set; }
+
+    public required PersonName Name { get; set; }
+
+    public List<string> Roles { get; set; } = new();
+
+    public required string UserId { get; set; }
+
+    public required string Id { get; set; }
 }
\ No newline at end of file
diff --git a/src/Application.Resources.Shared/UserProfile.cs b/src/Application.Resources.Shared/UserProfile.cs
index 4e80cfaf..016b0dfc 100644
--- a/src/Application.Resources.Shared/UserProfile.cs
+++ b/src/Application.Resources.Shared/UserProfile.cs
@@ -19,14 +19,14 @@ public class UserProfile : IIdentifiableResource
 
     public string? Timezone { get; set; }
 
-    public UserProfileType Type { get; set; }
+    public UserProfileClassification Classification { get; set; }
 
     public required string UserId { get; set; }
 
     public required string Id { get; set; }
 }
 
-public enum UserProfileType
+public enum UserProfileClassification
 {
     Person = 0,
     Machine = 1
diff --git a/src/Application.Services.Shared/IEndUsersService.cs b/src/Application.Services.Shared/IEndUsersService.cs
index 13dd8560..b6a8888b 100644
--- a/src/Application.Services.Shared/IEndUsersService.cs
+++ b/src/Application.Services.Shared/IEndUsersService.cs
@@ -15,12 +15,17 @@ Task<Result<Optional<EndUser>, Error>> FindPersonByEmailPrivateAsync(ICallerCont
     Task<Result<EndUserWithMemberships, Error>> GetMembershipsPrivateAsync(ICallerContext caller, string id,
         CancellationToken cancellationToken);
 
+    Task<Result<Membership, Error>> InviteMemberToOrganizationPrivateAsync(ICallerContext caller, string organizationId,
+        string? userId, string? emailAddress, CancellationToken cancellationToken);
+
+    Task<Result<SearchResults<MembershipWithUserProfile>, Error>> ListMembershipsForOrganizationAsync(
+        ICallerContext caller,
+        string organizationId, SearchOptions searchOptions, GetOptions getOptions, CancellationToken cancellationToken);
+
     Task<Result<RegisteredEndUser, Error>> RegisterMachinePrivateAsync(ICallerContext caller, string name,
-        string? timezone,
-        string? countryCode, CancellationToken cancellationToken);
+        string? timezone, string? countryCode, CancellationToken cancellationToken);
 
     Task<Result<RegisteredEndUser, Error>> RegisterPersonPrivateAsync(ICallerContext caller, string? invitationToken,
-        string emailAddress,
-        string firstName, string? lastName, string? timezone, string? countryCode, bool termsAndConditionsAccepted,
-        CancellationToken cancellationToken);
+        string emailAddress, string firstName, string? lastName, string? timezone, string? countryCode,
+        bool termsAndConditionsAccepted, CancellationToken cancellationToken);
 }
\ No newline at end of file
diff --git a/src/Application.Services.Shared/IUserProfilesService.cs b/src/Application.Services.Shared/IUserProfilesService.cs
index 1c05bd1a..62bc3705 100644
--- a/src/Application.Services.Shared/IUserProfilesService.cs
+++ b/src/Application.Services.Shared/IUserProfilesService.cs
@@ -17,6 +17,9 @@ Task<Result<UserProfile, Error>> CreatePersonProfilePrivateAsync(ICallerContext
     Task<Result<Optional<UserProfile>, Error>> FindPersonByEmailAddressPrivateAsync(ICallerContext caller,
         string emailAddress, CancellationToken cancellationToken);
 
+    Task<Result<List<UserProfile>, Error>> GetAllProfilesPrivateAsync(ICallerContext caller, List<string> ids,
+        GetOptions options, CancellationToken cancellationToken);
+
     Task<Result<UserProfile, Error>> GetProfilePrivateAsync(ICallerContext caller, string userId,
         CancellationToken cancellationToken);
 }
\ No newline at end of file
diff --git a/src/EndUsersApplication.UnitTests/EndUsersApplicationSpec.cs b/src/EndUsersApplication.UnitTests/EndUsersApplicationSpec.cs
index 0492b61a..4f3abc30 100644
--- a/src/EndUsersApplication.UnitTests/EndUsersApplicationSpec.cs
+++ b/src/EndUsersApplication.UnitTests/EndUsersApplicationSpec.cs
@@ -124,7 +124,7 @@ public async Task WhenRegisterPersonAsyncAndWasInvitedAsGuest_ThenCompletesRegis
             .ReturnsAsync(new UserProfile
             {
                 Id = "aprofileid",
-                Type = UserProfileType.Person,
+                Classification = UserProfileClassification.Person,
                 UserId = "apersonid",
                 DisplayName = "afirstname",
                 Name = new PersonName
@@ -206,7 +206,7 @@ await invitee.InviteGuestAsync(tokensService.Object, "aninviterid".ToId(),
             .ReturnsAsync(new UserProfile
             {
                 Id = "aprofileid",
-                Type = UserProfileType.Person,
+                Classification = UserProfileClassification.Person,
                 UserId = "apersonid",
                 DisplayName = "afirstname",
                 Name = new PersonName
@@ -276,7 +276,7 @@ public async Task WhenRegisterPersonAsyncAndAcceptingAnUnknownInvitation_ThenReg
             .ReturnsAsync(new UserProfile
             {
                 Id = "aprofileid",
-                Type = UserProfileType.Person,
+                Classification = UserProfileClassification.Person,
                 UserId = "apersonid",
                 DisplayName = "afirstname",
                 Name = new PersonName
@@ -346,7 +346,7 @@ public async Task
             .ReturnsAsync(new UserProfile
             {
                 Id = "anotherprofileid",
-                Type = UserProfileType.Person,
+                Classification = UserProfileClassification.Person,
                 UserId = "anotherpersonid",
                 DisplayName = "afirstname",
                 Name = new PersonName
@@ -394,7 +394,7 @@ public async Task WhenRegisterPersonAsyncAndAlreadyRegistered_ThenSendsCourtesyE
             .ReturnsAsync(new UserProfile
             {
                 Id = "aprofileid",
-                Type = UserProfileType.Person,
+                Classification = UserProfileClassification.Person,
                 UserId = "auserid",
                 DisplayName = "afirstname",
                 Name = new PersonName
@@ -468,7 +468,7 @@ public async Task WhenRegisterPersonAsyncAndNeverRegisteredNorInvitedAsGuest_The
             .ReturnsAsync(new UserProfile
             {
                 Id = "aprofileid",
-                Type = UserProfileType.Person,
+                Classification = UserProfileClassification.Person,
                 UserId = "apersonid",
                 DisplayName = "afirstname",
                 Name = new PersonName
@@ -523,7 +523,7 @@ public async Task WhenRegisterMachineAsyncByAnonymousUser_ThenRegistersWithNoFea
             .ReturnsAsync(new UserProfile
             {
                 Id = "aprofileid",
-                Type = UserProfileType.Machine,
+                Classification = UserProfileClassification.Machine,
                 UserId = "amachineid",
                 DisplayName = "amachinename",
                 Name = new PersonName
@@ -582,7 +582,7 @@ public async Task WhenRegisterMachineAsyncByAuthenticatedUser_ThenRegistersWithB
             .ReturnsAsync(new UserProfile
             {
                 Id = "aprofileid",
-                Type = UserProfileType.Machine,
+                Classification = UserProfileClassification.Machine,
                 UserId = "amachineid",
                 DisplayName = "amachinename",
                 Name = new PersonName
diff --git a/src/EndUsersApplication.UnitTests/InvitationsApplicationSpec.cs b/src/EndUsersApplication.UnitTests/InvitationsApplicationSpec.cs
index 9096fef5..86cfcaa3 100644
--- a/src/EndUsersApplication.UnitTests/InvitationsApplicationSpec.cs
+++ b/src/EndUsersApplication.UnitTests/InvitationsApplicationSpec.cs
@@ -23,7 +23,7 @@ public class InvitationsApplicationSpec
 {
     private readonly InvitationsApplication _application;
     private readonly Mock<ICallerContext> _caller;
-    private readonly Mock<IInvitationRepository> _repository;
+    private readonly Mock<IInvitationRepository> _invitationRepository;
     private readonly Mock<INotificationsService> _notificationsService;
     private readonly Mock<IRecorder> _recorder;
     private readonly Mock<ITokensService> _tokensService;
@@ -40,11 +40,8 @@ public InvitationsApplicationSpec()
         settings.Setup(
                 s => s.Platform.GetString(EndUsersApplication.PermittedOperatorsSettingName, It.IsAny<string?>()))
             .Returns("");
-        _repository = new Mock<IInvitationRepository>();
-        _repository.Setup(rep => rep.SaveAsync(It.IsAny<EndUserRoot>(), It.IsAny<CancellationToken>()))
-            .Returns((EndUserRoot root, CancellationToken _) => Task.FromResult<Result<EndUserRoot, Error>>(root));
-        var endUserRepository = new Mock<IEndUserRepository>();
-        endUserRepository.Setup(rep => rep.SaveAsync(It.IsAny<EndUserRoot>(), It.IsAny<CancellationToken>()))
+        _invitationRepository = new Mock<IInvitationRepository>();
+        _invitationRepository.Setup(rep => rep.SaveAsync(It.IsAny<EndUserRoot>(), It.IsAny<CancellationToken>()))
             .Returns((EndUserRoot root, CancellationToken _) => Task.FromResult<Result<EndUserRoot, Error>>(root));
         _userProfilesService = new Mock<IUserProfilesService>();
         _notificationsService = new Mock<INotificationsService>();
@@ -54,7 +51,7 @@ public InvitationsApplicationSpec()
 
         _application =
             new InvitationsApplication(_recorder.Object, idFactory.Object, _tokensService.Object,
-                _notificationsService.Object, _userProfilesService.Object, _repository.Object);
+                _notificationsService.Object, _userProfilesService.Object, _invitationRepository.Object);
     }
 
     [Fact]
@@ -64,15 +61,15 @@ public async Task WhenInviteGuestAsyncAndInviteeAlreadyRegistered_ThenReturnsErr
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
         var invitee = EndUserRoot
             .Create(_recorder.Object, "aninviteeid".ToIdentifierFactory(), UserClassification.Person).Value;
         invitee.Register(Roles.Empty, Features.Empty, EmailAddress.Create("aninvitee@company.com").Value);
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByEmailAddressAsync(It.IsAny<EmailAddress>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(invitee.ToOptional());
-        _repository.Setup(rep => rep.LoadAsync("aninviteeid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviteeid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(invitee);
         _userProfilesService.Setup(ups =>
                 ups.GetProfilePrivateAsync(It.IsAny<ICallerContext>(), "aninviterid", It.IsAny<CancellationToken>()))
@@ -94,19 +91,19 @@ public async Task WhenInviteGuestAsyncAndInviteeAlreadyRegistered_ThenReturnsErr
         _notificationsService.Verify(ns => ns.NotifyGuestInvitationToPlatformAsync(It.IsAny<ICallerContext>(),
             It.IsAny<string>(),
             It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>(), It.IsAny<CancellationToken>()), Times.Never);
-        _repository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
+        _invitationRepository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
     }
 
     [Fact]
-    public async Task WhenInviteGuestAsyncAndEmailOwnerAlreadyRegistered_ThenReturnsError()
+    public async Task WhenInviteGuestAsyncAndEmailOwnerAlreadyRegistered_ThenDoesNothing()
     {
         _caller.Setup(cc => cc.CallerId)
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByEmailAddressAsync(It.IsAny<EmailAddress>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(Optional<EndUserRoot>.None);
         _userProfilesService.Setup(ups =>
@@ -117,23 +114,33 @@ public async Task WhenInviteGuestAsyncAndEmailOwnerAlreadyRegistered_ThenReturns
                 DisplayName = "adisplayname",
                 Name = new PersonName
                 {
-                    FirstName = "afirstname"
+                    FirstName = "afirstname",
+                    LastName = "alastname"
                 },
-                UserId = "anotheruserid",
+                EmailAddress = "aninvitee@company.com",
+                UserId = "aninviteeid",
                 Id = "aprofileid"
             }.ToOptional());
+        var invitee = EndUserRoot
+            .Create(_recorder.Object, "aninviteeid".ToIdentifierFactory(), UserClassification.Person).Value;
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviteeid".ToId(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(invitee);
 
         var result =
             await _application.InviteGuestAsync(_caller.Object, "aninvitee@company.com", CancellationToken.None);
 
-        result.Should().BeError(ErrorCode.EntityExists, Resources.EndUsersApplication_GuestAlreadyRegistered);
+        result.Should().BeSuccess();
+        result.Value.EmailAddress.Should().Be("aninvitee@company.com");
+        result.Value.FirstName.Should().Be("afirstname");
+        result.Value.LastName.Should().Be("alastname");
         _notificationsService.Verify(ns => ns.NotifyGuestInvitationToPlatformAsync(It.IsAny<ICallerContext>(),
             It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>(),
             It.IsAny<CancellationToken>()), Times.Never);
         _userProfilesService.Verify(ups =>
             ups.FindPersonByEmailAddressPrivateAsync(_caller.Object, "aninvitee@company.com",
                 It.IsAny<CancellationToken>()));
-        _repository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
+        _invitationRepository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
+        _invitationRepository.Verify(rep => rep.LoadAsync("aninviteeid".ToId(), It.IsAny<CancellationToken>()));
     }
 
     [Fact]
@@ -143,16 +150,16 @@ public async Task WhenInviteGuestAsyncAndAlreadyInvited_ThenReInvitesGuest()
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
         var invitee = EndUserRoot
             .Create(_recorder.Object, "aninviteeid".ToIdentifierFactory(), UserClassification.Person).Value;
         await invitee.InviteGuestAsync(_tokensService.Object, "aninviterid".ToId(),
             EmailAddress.Create("aninvitee@company.com").Value, (_, _) => Task.FromResult(Result.Ok));
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByEmailAddressAsync(It.IsAny<EmailAddress>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(invitee.ToOptional());
-        _repository.Setup(rep => rep.LoadAsync("aninviteeid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviteeid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(invitee);
         _userProfilesService.Setup(ups =>
                 ups.GetProfilePrivateAsync(It.IsAny<ICallerContext>(), "aninviterid", It.IsAny<CancellationToken>()))
@@ -185,9 +192,9 @@ public async Task WhenInviteGuestAsync_ThenInvitesGuest()
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByEmailAddressAsync(It.IsAny<EmailAddress>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(Optional<EndUserRoot>.None);
         _userProfilesService.Setup(ups =>
@@ -219,8 +226,8 @@ public async Task WhenInviteGuestAsync_ThenInvitesGuest()
                 It.IsAny<CancellationToken>()));
         _notificationsService.Verify(ns => ns.NotifyGuestInvitationToPlatformAsync(_caller.Object, "aninvitationtoken",
             "aninvitee@company.com", "Aninvitee", "aninviterdisplayname", It.IsAny<CancellationToken>()));
-        _repository.Verify(rep => rep.LoadAsync("anid".ToId(), It.IsAny<CancellationToken>()), Times.Never);
-        _repository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
+        _invitationRepository.Verify(rep => rep.LoadAsync("anid".ToId(), It.IsAny<CancellationToken>()), Times.Never);
+        _invitationRepository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
     }
 
     [Fact]
@@ -230,9 +237,9 @@ public async Task WhenResendGuestInvitationAsyncAndInvitationNotExists_ThenRetur
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByTokenAsync(It.IsAny<string>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(Optional<EndUserRoot>.None);
 
@@ -249,13 +256,13 @@ public async Task WhenResendGuestInvitationAsyncAndInvitationExists_ThenReInvite
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
         var invitee = EndUserRoot
             .Create(_recorder.Object, "aninviteeid".ToIdentifierFactory(), UserClassification.Person).Value;
         await invitee.InviteGuestAsync(_tokensService.Object, "aninviterid".ToId(),
             EmailAddress.Create("aninvitee@company.com").Value, (_, _) => Task.FromResult(Result.Ok));
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByTokenAsync(It.IsAny<string>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(invitee.ToOptional());
         _userProfilesService.Setup(ups =>
@@ -277,8 +284,8 @@ await invitee.InviteGuestAsync(_tokensService.Object, "aninviterid".ToId(),
         result.Should().BeSuccess();
         _notificationsService.Verify(ns => ns.NotifyGuestInvitationToPlatformAsync(_caller.Object, "aninvitationtoken",
             "aninvitee@company.com", "Aninvitee", "aninviterdisplayname", It.IsAny<CancellationToken>()));
-        _repository.Verify(rep => rep.LoadAsync("anid".ToId(), It.IsAny<CancellationToken>()), Times.Never);
-        _repository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
+        _invitationRepository.Verify(rep => rep.LoadAsync("anid".ToId(), It.IsAny<CancellationToken>()), Times.Never);
+        _invitationRepository.Verify(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()));
     }
 
     [Fact]
@@ -288,9 +295,9 @@ public async Task WhenVerifyGuestInvitationAsyncAndInvitationNotExists_ThenRetur
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByTokenAsync(It.IsAny<string>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(Optional<EndUserRoot>.None);
 
@@ -307,13 +314,13 @@ public async Task WhenVerifyGuestInvitationAsyncAndInvitationExists_ThenVerifies
             .Returns("aninviterid");
         var inviter = EndUserRoot
             .Create(_recorder.Object, "aninviterid".ToIdentifierFactory(), UserClassification.Person).Value;
-        _repository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
+        _invitationRepository.Setup(rep => rep.LoadAsync("aninviterid".ToId(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(inviter);
         var invitee = EndUserRoot
             .Create(_recorder.Object, "aninviteeid".ToIdentifierFactory(), UserClassification.Person).Value;
         await invitee.InviteGuestAsync(_tokensService.Object, "aninviterid".ToId(),
             EmailAddress.Create("aninvitee@company.com").Value, (_, _) => Task.FromResult(Result.Ok));
-        _repository.Setup(rep =>
+        _invitationRepository.Setup(rep =>
                 rep.FindInvitedGuestByTokenAsync(It.IsAny<string>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(invitee.ToOptional());
 
diff --git a/src/EndUsersApplication/EndUsersApplication.cs b/src/EndUsersApplication/EndUsersApplication.cs
index d02ab56b..10d3565f 100644
--- a/src/EndUsersApplication/EndUsersApplication.cs
+++ b/src/EndUsersApplication/EndUsersApplication.cs
@@ -9,7 +9,9 @@
 using Domain.Common.ValueObjects;
 using Domain.Shared;
 using EndUsersApplication.Persistence;
+using EndUsersApplication.Persistence.ReadModels;
 using EndUsersDomain;
+using EndUser = Application.Resources.Shared.EndUser;
 using Membership = Application.Resources.Shared.Membership;
 using PersonName = Domain.Shared.PersonName;
 
@@ -59,6 +61,28 @@ public async Task<Result<EndUser, Error>> GetPersonAsync(ICallerContext context,
         return user.ToUser();
     }
 
+    public async Task<Result<SearchResults<MembershipWithUserProfile>, Error>> ListMembershipsForOrganizationAsync(
+        ICallerContext caller, string organizationId, SearchOptions searchOptions,
+        GetOptions getOptions, CancellationToken cancellationToken)
+    {
+        var retrieved =
+            await _endUserRepository.SearchAllMembershipsByOrganizationAsync(organizationId.ToId(), searchOptions,
+                cancellationToken);
+        if (!retrieved.IsSuccessful)
+        {
+            return retrieved.Error;
+        }
+
+        var members = retrieved.Value;
+        if (!IsMember(caller.ToCallerId(), members))
+        {
+            return Error.ForbiddenAccess(Resources.EndUsersApplication_CallerNotMember);
+        }
+
+        return searchOptions.ApplyWithMetadata(
+            await WithGetOptionsAsync(caller, members, getOptions, cancellationToken));
+    }
+
     public async Task<Result<EndUserWithMemberships, Error>> GetMembershipsAsync(ICallerContext context, string id,
         CancellationToken cancellationToken)
     {
@@ -94,8 +118,7 @@ public async Task<Result<RegisteredEndUser, Error>> RegisterMachineAsync(ICaller
 
         var profile = profiled.Value;
         var (platformRoles, platformFeatures, tenantRoles, tenantFeatures) =
-            EndUserRoot.GetInitialRolesAndFeatures(UserClassification.Machine, context.IsAuthenticated,
-                Optional<EmailAddress>.None, Optional<List<EmailAddress>>.None);
+            EndUserRoot.GetInitialRolesAndFeatures(RolesAndFeaturesUseCase.CreatingMachine, context.IsAuthenticated);
         var registered = machine.Register(platformRoles, platformFeatures, Optional<EmailAddress>.None);
         if (!registered.IsSuccessful)
         {
@@ -126,9 +149,12 @@ await _organizationsService.CreateOrganizationPrivateAsync(context, machine.Id,
                 return adder.Error;
             }
 
+            var (_, _, tenantRoles2, tenantFeatures2) =
+                EndUserRoot.GetInitialRolesAndFeatures(RolesAndFeaturesUseCase.InvitingMachineToCreatorOrg,
+                    context.IsAuthenticated);
             var adderDefaultOrganizationId = adder.Value.Memberships.DefaultMembership.OrganizationId;
-            var adderEnrolled = machine.AddMembership(adderDefaultOrganizationId, tenantRoles,
-                tenantFeatures);
+            var adderEnrolled = machine.AddMembership(adderDefaultOrganizationId, tenantRoles2,
+                tenantFeatures2);
             if (!adderEnrolled.IsSuccessful)
             {
                 return adderEnrolled.Error;
@@ -223,7 +249,7 @@ public async Task<Result<RegisteredEndUser, Error>> RegisterPersonAsync(ICallerC
             {
                 profile = existingUser.Value.Profile;
                 if (profile.NotExists()
-                    || profile.Type != UserProfileType.Person
+                    || profile.Classification != UserProfileClassification.Person
                     || profile.EmailAddress.HasNoValue())
                 {
                     return Error.EntityNotFound(Resources.EndUsersApplication_NotPersonProfile);
@@ -271,7 +297,8 @@ public async Task<Result<RegisteredEndUser, Error>> RegisterPersonAsync(ICallerC
         profile = profiled.Value;
         var permittedOperators = GetPermittedOperators();
         var (platformRoles, platformFeatures, tenantRoles, tenantFeatures) =
-            EndUserRoot.GetInitialRolesAndFeatures(UserClassification.Person, context.IsAuthenticated, username,
+            EndUserRoot.GetInitialRolesAndFeatures(RolesAndFeaturesUseCase.CreatingPerson, context.IsAuthenticated,
+                username,
                 permittedOperators);
         var registered = unregisteredUser.Register(platformRoles, platformFeatures, username);
         if (!registered.IsSuccessful)
@@ -328,9 +355,7 @@ public async Task<Result<Membership, Error>> CreateMembershipForCallerAsync(ICal
 
         var user = retrieved.Value;
         var (_, _, tenantRoles, tenantFeatures) =
-            EndUserRoot.GetInitialRolesAndFeatures(UserClassification.Person, context.IsAuthenticated,
-                Optional<EmailAddress>.None,
-                Optional<List<EmailAddress>>.None);
+            EndUserRoot.GetInitialRolesAndFeatures(RolesAndFeaturesUseCase.CreatingOrg, context.IsAuthenticated);
         var membered = user.AddMembership(organizationId.ToId(), tenantRoles, tenantFeatures);
         if (!membered.IsSuccessful)
         {
@@ -516,6 +541,42 @@ public async Task<Result<EndUserWithMemberships, Error>> AssignTenantRolesAsync(
         return assignee.ToUserWithMemberships();
     }
 
+    private async Task<IEnumerable<MembershipWithUserProfile>> WithGetOptionsAsync(ICallerContext caller,
+        List<MembershipJoinInvitation> memberships, GetOptions options, CancellationToken cancellationToken)
+    {
+        var ids = memberships
+            .Where(membership => membership.Status.Value.ToEnumOrDefault(EndUserStatus.Unregistered)
+                                 == EndUserStatus.Registered)
+            .Select(membership => membership.UserId.Value).ToList();
+
+        var profiles = new List<UserProfile>();
+        if (ids.Count > 0)
+        {
+            var retrieved =
+                await _userProfilesService.GetAllProfilesPrivateAsync(caller, ids, options, cancellationToken);
+            if (retrieved.IsSuccessful)
+            {
+                profiles = retrieved.Value;
+            }
+        }
+
+        return memberships.ConvertAll(membership =>
+        {
+            var member = membership.ToMembership();
+            member.Profile = membership.Status.Value.ToEnumOrDefault(EndUserStatus.Unregistered)
+                             == EndUserStatus.Unregistered
+                ? membership.ToUnregisteredUserProfile()
+                : profiles.First(profile => profile.UserId == membership.UserId);
+
+            return member;
+        });
+    }
+
+    private static bool IsMember(Identifier userId, List<MembershipJoinInvitation> members)
+    {
+        return members.Any(ms => ms.UserId.Value.EqualsIgnoreCase(userId));
+    }
+
     private async Task<Result<Optional<EndUserWithProfile>, Error>>
         FindRegisteredPersonOrInvitedGuestByEmailAddressAsync(ICallerContext caller, EmailAddress emailAddress,
             CancellationToken cancellationToken)
@@ -622,11 +683,29 @@ private record EndUserWithProfile(EndUserRoot User, UserProfile? Profile);
 
 internal static class EndUserConversionExtensions
 {
+    public static MembershipWithUserProfile ToMembership(this MembershipJoinInvitation membership)
+    {
+        var dto = new MembershipWithUserProfile
+        {
+            Id = membership.Id.Value,
+            UserId = membership.UserId.Value,
+            IsDefault = membership.IsDefault,
+            OrganizationId = membership.UserId.Value,
+            Status = membership.Status.Value.ToEnumOrDefault(EndUserStatus.Unregistered),
+            Roles = membership.Roles.Value.ToList(),
+            Features = membership.Features.Value.ToList(),
+            Profile = null!
+        };
+
+        return dto;
+    }
+
     public static Membership ToMembership(this EndUsersDomain.Membership ms)
     {
         return new Membership
         {
             Id = ms.Id,
+            UserId = ms.RootId.Value,
             IsDefault = ms.IsDefault,
             OrganizationId = ms.OrganizationId.Value,
             Features = ms.Features.ToList(),
@@ -645,6 +724,25 @@ public static RegisteredEndUser ToRegisteredUser(this EndUserRoot user, Identifi
         return registeredUser;
     }
 
+    public static UserProfile ToUnregisteredUserProfile(this MembershipJoinInvitation membership)
+    {
+        var dto = new UserProfile
+        {
+            Id = membership.UserId.Value,
+            UserId = membership.UserId.Value,
+            EmailAddress = membership.InvitedEmailAddress.Value,
+            DisplayName = membership.InvitedEmailAddress.Value,
+            Name = new Application.Resources.Shared.PersonName
+            {
+                FirstName = membership.InvitedEmailAddress.Value,
+                LastName = null
+            },
+            Classification = UserProfileClassification.Person
+        };
+
+        return dto;
+    }
+
     public static EndUser ToUser(this EndUserRoot user)
     {
         return new EndUser
diff --git a/src/EndUsersApplication/IEndUsersApplication.cs b/src/EndUsersApplication/IEndUsersApplication.cs
index 8c2e37f5..7daf27d8 100644
--- a/src/EndUsersApplication/IEndUsersApplication.cs
+++ b/src/EndUsersApplication/IEndUsersApplication.cs
@@ -24,6 +24,10 @@ Task<Result<EndUserWithMemberships, Error>> GetMembershipsAsync(ICallerContext c
 
     Task<Result<EndUser, Error>> GetPersonAsync(ICallerContext context, string id, CancellationToken cancellationToken);
 
+    Task<Result<SearchResults<MembershipWithUserProfile>, Error>> ListMembershipsForOrganizationAsync(
+        ICallerContext caller,
+        string organizationId, SearchOptions searchOptions, GetOptions getOptions, CancellationToken cancellationToken);
+
     Task<Result<RegisteredEndUser, Error>> RegisterMachineAsync(ICallerContext context, string name, string? timezone,
         string? countryCode, CancellationToken cancellationToken);
 
diff --git a/src/EndUsersApplication/IInvitationsApplication.cs b/src/EndUsersApplication/IInvitationsApplication.cs
index 0ed68df4..7d656f22 100644
--- a/src/EndUsersApplication/IInvitationsApplication.cs
+++ b/src/EndUsersApplication/IInvitationsApplication.cs
@@ -9,6 +9,9 @@ public interface IInvitationsApplication
     Task<Result<Invitation, Error>> InviteGuestAsync(ICallerContext context, string emailAddress,
         CancellationToken cancellationToken);
 
+    Task<Result<Membership, Error>> InviteMemberToOrganizationAsync(ICallerContext context, string organizationId,
+        string? userId, string? emailAddress, CancellationToken cancellationToken);
+
     Task<Result<Error>> ResendGuestInvitationAsync(ICallerContext context, string token,
         CancellationToken cancellationToken);
 
diff --git a/src/EndUsersApplication/InvitationsApplication.cs b/src/EndUsersApplication/InvitationsApplication.cs
index 54496cb3..832908cc 100644
--- a/src/EndUsersApplication/InvitationsApplication.cs
+++ b/src/EndUsersApplication/InvitationsApplication.cs
@@ -3,19 +3,21 @@
 using Application.Resources.Shared;
 using Application.Services.Shared;
 using Common;
+using Common.Extensions;
 using Domain.Common.Identity;
 using Domain.Common.ValueObjects;
 using Domain.Services.Shared.DomainServices;
 using Domain.Shared;
 using EndUsersApplication.Persistence;
 using EndUsersDomain;
+using Membership = Application.Resources.Shared.Membership;
 
 namespace EndUsersApplication;
 
 public class InvitationsApplication : IInvitationsApplication
 {
     private readonly IIdentifierFactory _idFactory;
-    private readonly IInvitationRepository _repository;
+    private readonly IInvitationRepository _invitationsRepository;
     private readonly INotificationsService _notificationsService;
     private readonly IRecorder _recorder;
     private readonly ITokensService _tokensService;
@@ -23,102 +25,100 @@ public class InvitationsApplication : IInvitationsApplication
 
     public InvitationsApplication(IRecorder recorder, IIdentifierFactory idFactory, ITokensService tokensService,
         INotificationsService notificationsService, IUserProfilesService userProfilesService,
-        IInvitationRepository repository)
+        IInvitationRepository invitationsRepository)
     {
         _recorder = recorder;
         _idFactory = idFactory;
         _tokensService = tokensService;
         _notificationsService = notificationsService;
         _userProfilesService = userProfilesService;
-        _repository = repository;
+        _invitationsRepository = invitationsRepository;
     }
 
     public async Task<Result<Invitation, Error>> InviteGuestAsync(ICallerContext context, string emailAddress,
         CancellationToken cancellationToken)
     {
-        var retrievedInviter = await _repository.LoadAsync(context.ToCallerId(), cancellationToken);
-        if (!retrievedInviter.IsSuccessful)
+        var invited = await InviteGuestByEmailInternalAsync(context, emailAddress, cancellationToken);
+        if (!invited.IsSuccessful)
         {
-            return retrievedInviter.Error;
+            return invited.Error;
         }
 
-        var inviter = retrievedInviter.Value;
-
-        var email = EmailAddress.Create(emailAddress);
-        if (!email.IsSuccessful)
+        var invitee = invited.Value.Invitee;
+        var saved = await _invitationsRepository.SaveAsync(invitee, cancellationToken);
+        if (!saved.IsSuccessful)
         {
-            return email.Error;
+            return saved.Error;
         }
 
-        var retrievedGuest =
-            await _repository.FindInvitedGuestByEmailAddressAsync(email.Value, cancellationToken);
-        if (!retrievedGuest.IsSuccessful)
+        _recorder.TraceInformation(context.ToCall(), "Guest {Id} was invited", invitee.Id);
+        _recorder.TrackUsage(context.ToCall(), UsageConstants.Events.UsageScenarios.GuestInvited,
+            new Dictionary<string, object>
+            {
+                { nameof(EndUserRoot.Id), invitee.Id },
+                { nameof(UserProfile.EmailAddress), emailAddress }
+            });
+
+        return invited.Value.Invitee.ToInvitation(invited.Value.Profile);
+    }
+
+    public async Task<Result<Membership, Error>> InviteMemberToOrganizationAsync(ICallerContext context,
+        string organizationId, string? userId, string? emailAddress, CancellationToken cancellationToken)
+    {
+        if (emailAddress.HasNoValue() && userId.HasNoValue())
         {
-            return retrievedGuest.Error;
+            return Error.RuleViolation(Resources
+                .InvitationsApplication_InviteToOrganizationWithoutEmailAddressOrUserId);
         }
 
         EndUserRoot invitee;
-        if (retrievedGuest.Value.HasValue)
+        if (emailAddress.HasValue())
         {
-            invitee = retrievedGuest.Value.Value;
-            if (invitee.Status == UserStatus.Registered)
+            var invited = await InviteGuestByEmailInternalAsync(context, emailAddress, cancellationToken);
+            if (!invited.IsSuccessful)
             {
-                return Error.EntityExists(Resources.EndUsersApplication_GuestAlreadyRegistered);
+                return invited.Error;
             }
+
+            invitee = invited.Value.Invitee;
         }
         else
         {
-            var retrievedEmailOwner =
-                await _userProfilesService.FindPersonByEmailAddressPrivateAsync(context, emailAddress,
-                    cancellationToken);
-            if (!retrievedEmailOwner.IsSuccessful)
+            var invited = await InviteGuestByUserIdInternalAsync(context, userId!, cancellationToken);
+            if (!invited.IsSuccessful)
             {
-                return retrievedEmailOwner.Error;
-            }
-
-            if (retrievedEmailOwner.Value.HasValue)
-            {
-                return Error.EntityExists(Resources.EndUsersApplication_GuestAlreadyRegistered);
+                return invited.Error;
             }
 
-            var created = EndUserRoot.Create(_recorder, _idFactory, UserClassification.Person);
-            if (!created.IsSuccessful)
-            {
-                return created.Error;
-            }
-
-            invitee = created.Value;
+            invitee = invited.Value.Invitee;
         }
 
-        var invited = await invitee.InviteGuestAsync(_tokensService, inviter.Id, email.Value,
-            async (inviterId, newToken) =>
-                await SendInvitationNotificationAsync(context, inviterId, newToken, invitee, cancellationToken));
-        if (!invited.IsSuccessful)
+        var (_, _, tenantRoles, tenantFeatures) =
+            EndUserRoot.GetInitialRolesAndFeatures(RolesAndFeaturesUseCase.InvitingMemberToOrg,
+                context.IsAuthenticated);
+        var enrolled = invitee.AddMembership(organizationId.ToId(), tenantRoles, tenantFeatures);
+        if (!enrolled.IsSuccessful)
         {
-            return invited.Error;
+            return enrolled.Error;
         }
 
-        var saved = await _repository.SaveAsync(invitee, cancellationToken);
+        var membership = invitee.FindMembership(organizationId.ToId());
+        var saved = await _invitationsRepository.SaveAsync(invitee, cancellationToken);
         if (!saved.IsSuccessful)
         {
             return saved.Error;
         }
 
-        _recorder.TraceInformation(context.ToCall(), "Guest {Id} was invited", invitee.Id);
-        _recorder.TrackUsage(context.ToCall(), UsageConstants.Events.UsageScenarios.GuestInvited,
-            new Dictionary<string, object>
-            {
-                { nameof(EndUserRoot.Id), invitee.Id },
-                { nameof(UserProfile.EmailAddress), invitee.GuestInvitation.InviteeEmailAddress!.Address }
-            });
+        _recorder.TraceInformation(context.ToCall(),
+            "EndUser {Id} has been invited to organization {Organization}", saved.Value.Id, organizationId);
 
-        return invitee.ToInvitation();
+        return membership.Value.ToMembership();
     }
 
     public async Task<Result<Error>> ResendGuestInvitationAsync(ICallerContext context, string token,
         CancellationToken cancellationToken)
     {
-        var retrievedInviter = await _repository.LoadAsync(context.ToCallerId(), cancellationToken);
+        var retrievedInviter = await _invitationsRepository.LoadAsync(context.ToCallerId(), cancellationToken);
         if (!retrievedInviter.IsSuccessful)
         {
             return retrievedInviter.Error;
@@ -126,7 +126,7 @@ public async Task<Result<Error>> ResendGuestInvitationAsync(ICallerContext conte
 
         var inviter = retrievedInviter.Value;
 
-        var retrievedGuest = await _repository.FindInvitedGuestByTokenAsync(token, cancellationToken);
+        var retrievedGuest = await _invitationsRepository.FindInvitedGuestByTokenAsync(token, cancellationToken);
         if (!retrievedGuest.IsSuccessful)
         {
             return retrievedGuest.Error;
@@ -147,7 +147,7 @@ public async Task<Result<Error>> ResendGuestInvitationAsync(ICallerContext conte
             return invited.Error;
         }
 
-        var saved = await _repository.SaveAsync(invitee, cancellationToken);
+        var saved = await _invitationsRepository.SaveAsync(invitee, cancellationToken);
         if (!saved.IsSuccessful)
         {
             return saved.Error;
@@ -167,7 +167,7 @@ public async Task<Result<Error>> ResendGuestInvitationAsync(ICallerContext conte
     public async Task<Result<Invitation, Error>> VerifyGuestInvitationAsync(ICallerContext context, string token,
         CancellationToken cancellationToken)
     {
-        var retrievedGuest = await _repository.FindInvitedGuestByTokenAsync(token, cancellationToken);
+        var retrievedGuest = await _invitationsRepository.FindInvitedGuestByTokenAsync(token, cancellationToken);
         if (!retrievedGuest.IsSuccessful)
         {
             return retrievedGuest.Error;
@@ -189,6 +189,124 @@ public async Task<Result<Invitation, Error>> VerifyGuestInvitationAsync(ICallerC
         return invitee.ToInvitation();
     }
 
+    private async Task<Result<(EndUserRoot Invitee, UserProfile? Profile), Error>> InviteGuestByEmailInternalAsync(
+        ICallerContext context,
+        string emailAddress, CancellationToken cancellationToken)
+    {
+        var retrievedInviter = await _invitationsRepository.LoadAsync(context.ToCallerId(), cancellationToken);
+        if (!retrievedInviter.IsSuccessful)
+        {
+            return retrievedInviter.Error;
+        }
+
+        var inviter = retrievedInviter.Value;
+
+        var email = EmailAddress.Create(emailAddress);
+        if (!email.IsSuccessful)
+        {
+            return email.Error;
+        }
+
+        var retrievedGuest =
+            await _invitationsRepository.FindInvitedGuestByEmailAddressAsync(email.Value, cancellationToken);
+        if (!retrievedGuest.IsSuccessful)
+        {
+            return retrievedGuest.Error;
+        }
+
+        EndUserRoot invitee;
+        if (retrievedGuest.Value.HasValue)
+        {
+            invitee = retrievedGuest.Value.Value;
+            if (invitee.Status == UserStatus.Registered)
+            {
+                return Error.EntityExists(Resources.EndUsersApplication_GuestAlreadyRegistered);
+            }
+        }
+        else
+        {
+            var retrievedEmailOwner =
+                await _userProfilesService.FindPersonByEmailAddressPrivateAsync(context, emailAddress,
+                    cancellationToken);
+            if (!retrievedEmailOwner.IsSuccessful)
+            {
+                return retrievedEmailOwner.Error;
+            }
+
+            if (retrievedEmailOwner.Value.HasValue)
+            {
+                var retrievedInvitee =
+                    await _invitationsRepository.LoadAsync(retrievedEmailOwner.Value.Value.UserId.ToId(),
+                        cancellationToken);
+                if (!retrievedInvitee.IsSuccessful)
+                {
+                    return retrievedInvitee.Error;
+                }
+
+                return (retrievedInvitee.Value, retrievedEmailOwner.Value.Value);
+            }
+
+            var created = EndUserRoot.Create(_recorder, _idFactory, UserClassification.Person);
+            if (!created.IsSuccessful)
+            {
+                return created.Error;
+            }
+
+            invitee = created.Value;
+        }
+
+        var invited = await invitee.InviteGuestAsync(_tokensService, inviter.Id, email.Value,
+            async (inviterId, newToken) =>
+                await SendInvitationNotificationAsync(context, inviterId, newToken, invitee, cancellationToken));
+        if (!invited.IsSuccessful)
+        {
+            return invited.Error;
+        }
+
+        return (invitee, null);
+    }
+
+    private async Task<Result<(EndUserRoot Invitee, UserProfile? Profile), Error>> InviteGuestByUserIdInternalAsync(
+        ICallerContext context,
+        string userId, CancellationToken cancellationToken)
+    {
+        var retrievedInviter = await _invitationsRepository.LoadAsync(context.ToCallerId(), cancellationToken);
+        if (!retrievedInviter.IsSuccessful)
+        {
+            return retrievedInviter.Error;
+        }
+
+        var inviter = retrievedInviter.Value;
+
+        var retrievedInvitee = await _invitationsRepository.LoadAsync(userId.ToId(), cancellationToken);
+        if (!retrievedInvitee.IsSuccessful)
+        {
+            return retrievedInvitee.Error;
+        }
+
+        var invitee = retrievedInvitee.Value;
+        if (invitee.IsRegistered)
+        {
+            return (invitee, null);
+        }
+
+        var email = EmailAddress.Create(invitee.GuestInvitation.InviteeEmailAddress!.Address);
+        if (!email.IsSuccessful)
+        {
+            return email.Error;
+        }
+
+        var invited = await invitee.InviteGuestAsync(_tokensService, inviter.Id, email.Value,
+            async (inviterId, newToken) =>
+                await SendInvitationNotificationAsync(context, inviterId, newToken, invitee, cancellationToken));
+        if (!invited.IsSuccessful)
+        {
+            return invited.Error;
+        }
+
+        return (invitee, null);
+    }
+
     private async Task<Result<Error>> SendInvitationNotificationAsync(ICallerContext context,
         Identifier inviterId, string token, EndUserRoot invitee, CancellationToken cancellationToken)
     {
@@ -216,8 +334,18 @@ await _notificationsService.NotifyGuestInvitationToPlatformAsync(context, token,
 
 internal static class InvitationConversionExtensions
 {
-    public static Invitation ToInvitation(this EndUserRoot invitee)
+    public static Invitation ToInvitation(this EndUserRoot invitee, UserProfile? profile = null)
     {
+        if (profile.Exists())
+        {
+            return new Invitation
+            {
+                EmailAddress = profile.EmailAddress!,
+                FirstName = profile.Name.FirstName,
+                LastName = profile.Name.LastName
+            };
+        }
+
         var assumedName = invitee.GuessGuestInvitationName();
         return new Invitation
         {
diff --git a/src/EndUsersApplication/Persistence/IEndUserRepository.cs b/src/EndUsersApplication/Persistence/IEndUserRepository.cs
index d41e9f1a..cd08c43b 100644
--- a/src/EndUsersApplication/Persistence/IEndUserRepository.cs
+++ b/src/EndUsersApplication/Persistence/IEndUserRepository.cs
@@ -1,6 +1,8 @@
+using Application.Interfaces;
 using Application.Persistence.Interfaces;
 using Common;
 using Domain.Common.ValueObjects;
+using EndUsersApplication.Persistence.ReadModels;
 using EndUsersDomain;
 
 namespace EndUsersApplication.Persistence;
@@ -10,4 +12,8 @@ public interface IEndUserRepository : IApplicationRepository
     Task<Result<EndUserRoot, Error>> LoadAsync(Identifier id, CancellationToken cancellationToken);
 
     Task<Result<EndUserRoot, Error>> SaveAsync(EndUserRoot user, CancellationToken cancellationToken);
+
+    Task<Result<List<MembershipJoinInvitation>, Error>> SearchAllMembershipsByOrganizationAsync(
+        Identifier organizationId,
+        SearchOptions searchOptions, CancellationToken cancellationToken);
 }
\ No newline at end of file
diff --git a/src/EndUsersApplication/Persistence/ReadModels/MembershipJoinInvitation.cs b/src/EndUsersApplication/Persistence/ReadModels/MembershipJoinInvitation.cs
new file mode 100644
index 00000000..8440e1ca
--- /dev/null
+++ b/src/EndUsersApplication/Persistence/ReadModels/MembershipJoinInvitation.cs
@@ -0,0 +1,24 @@
+using Application.Persistence.Common;
+using Common;
+using Domain.Shared;
+using QueryAny;
+
+namespace EndUsersApplication.Persistence.ReadModels;
+
+[EntityName("Membership")]
+public class MembershipJoinInvitation : ReadModelEntity
+{
+    public Optional<string> UserId { get; set; }
+
+    public Optional<string> OrganizationId { get; set; }
+
+    public bool IsDefault { get; set; }
+
+    public Optional<Roles> Roles { get; set; }
+
+    public Optional<Features> Features { get; set; }
+
+    public Optional<string> InvitedEmailAddress { get; set; }
+
+    public Optional<string> Status { get; set; }
+}
\ No newline at end of file
diff --git a/src/EndUsersApplication/Resources.Designer.cs b/src/EndUsersApplication/Resources.Designer.cs
index 35ebad1a..1a1d8f75 100644
--- a/src/EndUsersApplication/Resources.Designer.cs
+++ b/src/EndUsersApplication/Resources.Designer.cs
@@ -68,6 +68,15 @@ internal static string EndUsersApplication_AcceptedInvitationWithExistingEmailAd
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to The caller is not a member of this organization.
+        /// </summary>
+        internal static string EndUsersApplication_CallerNotMember {
+            get {
+                return ResourceManager.GetString("EndUsersApplication_CallerNotMember", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to This guest is already registered as a user.
         /// </summary>
@@ -103,5 +112,14 @@ internal static string EndUsersApplication_NotPersonProfile {
                 return ResourceManager.GetString("EndUsersApplication_NotPersonProfile", resourceCulture);
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cannot invite a user to an organization without either an email or user ID.
+        /// </summary>
+        internal static string InvitationsApplication_InviteToOrganizationWithoutEmailAddressOrUserId {
+            get {
+                return ResourceManager.GetString("InvitationsApplication_InviteToOrganizationWithoutEmailAddressOrUserId", resourceCulture);
+            }
+        }
     }
 }
diff --git a/src/EndUsersApplication/Resources.resx b/src/EndUsersApplication/Resources.resx
index 9cc996c3..c80ddd58 100644
--- a/src/EndUsersApplication/Resources.resx
+++ b/src/EndUsersApplication/Resources.resx
@@ -39,4 +39,10 @@
     <data name="EndUsersApplication_AcceptedInvitationWithExistingEmailAddress" xml:space="preserve">
         <value>A user with this email address is already registered</value>
     </data>
+    <data name="EndUsersApplication_CallerNotMember" xml:space="preserve">
+        <value>The caller is not a member of this organization</value>
+    </data>
+    <data name="InvitationsApplication_InviteToOrganizationWithoutEmailAddressOrUserId" xml:space="preserve">
+        <value>Cannot invite a user to an organization without either an email or user ID</value>
+    </data>
 </root>
\ No newline at end of file
diff --git a/src/EndUsersDomain.UnitTests/EndUserRootSpec.cs b/src/EndUsersDomain.UnitTests/EndUserRootSpec.cs
index 59aeffd8..459b1ae4 100644
--- a/src/EndUsersDomain.UnitTests/EndUserRootSpec.cs
+++ b/src/EndUsersDomain.UnitTests/EndUserRootSpec.cs
@@ -140,14 +140,6 @@ public void WhenEnsureInvariantsAndRegisteredPersonStillInvited_ThenReturnsError
         result.Should().BeError(ErrorCode.RuleViolation, Resources.EndUserRoot_GuestAlreadyRegistered);
     }
 
-    [Fact]
-    public void WhenAddMembershipAndNotRegistered_ThenReturnsError()
-    {
-        var result = _user.AddMembership("anorganizationid".ToId(), Roles.Create(), Features.Create());
-
-        result.Should().BeError(ErrorCode.RuleViolation, Resources.EndUserRoot_NotRegistered);
-    }
-
     [Fact]
     public void WhenAddMembershipAndAlreadyMember_ThenReturns()
     {
diff --git a/src/EndUsersDomain.UnitTests/MembershipSpec.cs b/src/EndUsersDomain.UnitTests/MembershipSpec.cs
index 456e96f4..23e0c59f 100644
--- a/src/EndUsersDomain.UnitTests/MembershipSpec.cs
+++ b/src/EndUsersDomain.UnitTests/MembershipSpec.cs
@@ -1,4 +1,5 @@
 using Common;
+using Common.Extensions;
 using Domain.Common.Identity;
 using Domain.Common.ValueObjects;
 using Domain.Interfaces.Authorization;
@@ -77,11 +78,30 @@ public void WhenMembershipFeatureAssignedEventRaised_ThenAssigned()
         _membership.Features.HasFeature(feature).Should();
     }
 
+    [Fact]
+    public void WhenEnsureInvariantsAndMissingDefaultRole_ThenReturnsError()
+    {
+        _membership.As<IEventingEntity>()
+            .RaiseEvent(Events.MembershipFeatureAssigned.Create("arootid".ToId(),
+                    "anorganizationid".ToId(), "amembershipid".ToId(), Feature.Create(Membership.DefaultFeature).Value),
+                true);
+
+        var result = _membership.EnsureInvariants();
+
+        result.Should().BeError(ErrorCode.RuleViolation,
+            Resources.Membership_MissingDefaultRole.Format(Membership.DefaultRole.Name));
+    }
+
     [Fact]
     public void WhenEnsureInvariantsAndMissingDefaultFeature_ThenReturnsError()
     {
+        _membership.As<IEventingEntity>()
+            .RaiseEvent(Events.MembershipRoleAssigned.Create("arootid".ToId(),
+                "anorganizationid".ToId(), "amembershipid".ToId(), Role.Create(Membership.DefaultRole).Value), true);
+        
         var result = _membership.EnsureInvariants();
 
-        result.Should().BeError(ErrorCode.RuleViolation, Resources.Membership_MissingDefaultFeature);
+        result.Should().BeError(ErrorCode.RuleViolation,
+            Resources.Membership_MissingDefaultFeature.Format(Membership.DefaultFeature.Name));
     }
 }
\ No newline at end of file
diff --git a/src/EndUsersDomain.UnitTests/MembershipsSpec.cs b/src/EndUsersDomain.UnitTests/MembershipsSpec.cs
index a9901aa2..1e639a7f 100644
--- a/src/EndUsersDomain.UnitTests/MembershipsSpec.cs
+++ b/src/EndUsersDomain.UnitTests/MembershipsSpec.cs
@@ -163,11 +163,12 @@ public void WhenEnsureInvariantsAndMoreThanOneForEachOrganization_ThenReturnsErr
 
     private Membership CreateMembership(string organizationId = "anorganizationid", bool isDefault = true)
     {
+        var roles = Roles.Create(Membership.DefaultRole).Value;
         var features = Features.Create(Membership.DefaultFeature).Value;
         var membership = Membership.Create(_recorder.Object, _idFactory.Object, _ => Result.Ok).Value;
         membership.As<IEventingEntity>()
             .RaiseEvent(Events.MembershipAdded.Create("arootid".ToId(),
-                organizationId.ToId(), isDefault, Roles.Empty, features), true);
+                organizationId.ToId(), isDefault, roles, features), true);
         return membership;
     }
 }
\ No newline at end of file
diff --git a/src/EndUsersDomain/EndUserRoot.cs b/src/EndUsersDomain/EndUserRoot.cs
index 12ba865f..34cb5afd 100644
--- a/src/EndUsersDomain/EndUserRoot.cs
+++ b/src/EndUsersDomain/EndUserRoot.cs
@@ -323,10 +323,7 @@ public Result<Error> AcceptGuestInvitation(Identifier acceptedById, EmailAddress
 
     public Result<Error> AddMembership(Identifier organizationId, Roles tenantRoles, Features tenantFeatures)
     {
-        if (!IsRegistered)
-        {
-            return Error.RuleViolation(Resources.EndUserRoot_NotRegistered);
-        }
+        //TODO: check that the adder is a member of this organization, and an owner of it
 
         var existing = Memberships.FindByOrganizationId(organizationId);
         if (existing.HasValue)
@@ -497,39 +494,57 @@ public Optional<Membership> FindMembership(Identifier organizationId)
     ///     EXTEND: change this to assign initial roles and features for persons and machines
     /// </summary>
     public static (Roles PlatformRoles, Features PlatformFeatures, Roles TenantRoles, Features TenantFeatures)
-        GetInitialRolesAndFeatures(UserClassification classification, bool isAuthenticated,
-            Optional<EmailAddress> username, Optional<List<EmailAddress>> permittedOperators)
+        GetInitialRolesAndFeatures(RolesAndFeaturesUseCase useCase, bool isAuthenticated,
+            EmailAddress? username = null, List<EmailAddress>? permittedOperators = null)
     {
         var platformRoles = Roles.Create();
         platformRoles = platformRoles.Add(PlatformRoles.Standard).Value;
-        if (username.HasValue && permittedOperators.HasValue)
+        if (username.Exists() && permittedOperators.Exists())
         {
-            if (permittedOperators.Value
+            if (permittedOperators
                 .Select(x => x.Address)
-                .ContainsIgnoreCase(username.Value))
+                .ContainsIgnoreCase(username))
             {
                 platformRoles = platformRoles.Add(PlatformRoles.Operations).Value;
             }
         }
 
-        var tenantRoles = Roles.Create();
-        tenantRoles = tenantRoles.Add(TenantRoles.Member).Value;
-
         var platformFeatures = Features.Create();
+        Roles tenantRoles;
         var tenantFeatures = Features.Create();
-        if (classification == UserClassification.Machine)
-        {
-            platformFeatures = platformFeatures.Add(isAuthenticated
-                ? PlatformFeatures.PaidTrial
-                : PlatformFeatures.Basic).Value;
-            tenantFeatures = tenantFeatures.Add(isAuthenticated
-                ? TenantFeatures.PaidTrial
-                : TenantFeatures.Basic).Value;
-        }
-        else
-        {
-            platformFeatures = platformFeatures.Add(PlatformFeatures.PaidTrial).Value;
-            tenantFeatures = tenantFeatures.Add(TenantFeatures.PaidTrial).Value;
+        switch (useCase)
+        {
+            case RolesAndFeaturesUseCase.CreatingMachine:
+                platformFeatures = platformFeatures.Add(isAuthenticated
+                    ? PlatformFeatures.PaidTrial
+                    : PlatformFeatures.Basic).Value;
+                tenantRoles = Roles.Create(TenantRoles.Owner, TenantRoles.Member).Value;
+                tenantFeatures = tenantFeatures.Add(isAuthenticated
+                    ? TenantFeatures.PaidTrial
+                    : TenantFeatures.Basic).Value;
+                break;
+
+            case RolesAndFeaturesUseCase.CreatingPerson:
+            case RolesAndFeaturesUseCase.CreatingOrg:
+                platformFeatures = platformFeatures.Add(PlatformFeatures.PaidTrial).Value;
+                tenantRoles = Roles.Create(TenantRoles.BillingAdmin, TenantRoles.Owner, TenantRoles.Member).Value;
+                tenantFeatures = tenantFeatures.Add(TenantFeatures.PaidTrial).Value;
+                break;
+
+            case RolesAndFeaturesUseCase.InvitingMemberToOrg:
+                platformFeatures = platformFeatures.Add(PlatformFeatures.PaidTrial).Value;
+                tenantFeatures = tenantFeatures.Add(TenantFeatures.PaidTrial).Value;
+                tenantRoles = Roles.Create(TenantRoles.Member).Value;
+                break;
+
+            case RolesAndFeaturesUseCase.InvitingMachineToCreatorOrg:
+                platformFeatures = platformFeatures.Add(PlatformFeatures.PaidTrial).Value;
+                tenantRoles = Roles.Create(TenantRoles.Member).Value;
+                tenantFeatures = tenantFeatures.Add(TenantFeatures.PaidTrial).Value;
+                break;
+
+            default:
+                throw new ArgumentOutOfRangeException(nameof(useCase), useCase, null);
         }
 
         return (platformRoles, platformFeatures, tenantRoles, tenantFeatures);
diff --git a/src/EndUsersDomain/Membership.cs b/src/EndUsersDomain/Membership.cs
index ef1578cd..6ab5203a 100644
--- a/src/EndUsersDomain/Membership.cs
+++ b/src/EndUsersDomain/Membership.cs
@@ -1,4 +1,5 @@
 using Common;
+using Common.Extensions;
 using Domain.Common.Entities;
 using Domain.Common.Identity;
 using Domain.Common.ValueObjects;
@@ -10,6 +11,7 @@ namespace EndUsersDomain;
 
 public sealed class Membership : EntityBase
 {
+    internal static readonly RoleLevel DefaultRole = TenantRoles.Member;
     internal static readonly FeatureLevel DefaultFeature = TenantFeatures.Basic;
 
     public static Result<Membership, Error> Create(IRecorder recorder, IIdentifierFactory idFactory,
@@ -111,9 +113,13 @@ public override Result<Error> EnsureInvariants()
             return ensureInvariants.Error;
         }
 
+        if (!Roles.HasRole(DefaultRole))
+        {
+            return Error.RuleViolation(Resources.Membership_MissingDefaultRole.Format(DefaultRole.Name));
+        }
         if (!Features.HasFeature(DefaultFeature))
         {
-            return Error.RuleViolation(Resources.Membership_MissingDefaultFeature);
+            return Error.RuleViolation(Resources.Membership_MissingDefaultFeature.Format(DefaultFeature.Name));
         }
 
         return Result.Ok;
diff --git a/src/EndUsersDomain/Resources.Designer.cs b/src/EndUsersDomain/Resources.Designer.cs
index f9a52617..a0e363b2 100644
--- a/src/EndUsersDomain/Resources.Designer.cs
+++ b/src/EndUsersDomain/Resources.Designer.cs
@@ -258,7 +258,7 @@ internal static string GuestInvitation_NotInvited {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to A membership must always have the default feature set.
+        ///   Looks up a localized string similar to A membership must always have at least the feature &apos;{0}&apos;.
         /// </summary>
         internal static string Membership_MissingDefaultFeature {
             get {
@@ -266,6 +266,15 @@ internal static string Membership_MissingDefaultFeature {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to A membership must always have at least the role &apos;{0}&apos;.
+        /// </summary>
+        internal static string Membership_MissingDefaultRole {
+            get {
+                return ResourceManager.GetString("Membership_MissingDefaultRole", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Cannot have multiple memberships for the same organization.
         /// </summary>
diff --git a/src/EndUsersDomain/Resources.resx b/src/EndUsersDomain/Resources.resx
index 540872c0..aed397d8 100644
--- a/src/EndUsersDomain/Resources.resx
+++ b/src/EndUsersDomain/Resources.resx
@@ -75,8 +75,11 @@
     <data name="EndUserRoot_NotOrganizationOwner" xml:space="preserve">
         <value>The assigner is not an owner of the organization</value>
     </data>
+    <data name="Membership_MissingDefaultRole" xml:space="preserve">
+        <value>A membership must always have at least the role '{0}'</value>
+    </data>
     <data name="Membership_MissingDefaultFeature" xml:space="preserve">
-        <value>A membership must always have the default feature set</value>
+        <value>A membership must always have at least the feature '{0}'</value>
     </data>
     <data name="EndUserRoot_NotOperator" xml:space="preserve">
         <value>The assigner is not a member of the operations team</value>
diff --git a/src/EndUsersDomain/RolesAndFeaturesUseCase.cs b/src/EndUsersDomain/RolesAndFeaturesUseCase.cs
new file mode 100644
index 00000000..0f72a286
--- /dev/null
+++ b/src/EndUsersDomain/RolesAndFeaturesUseCase.cs
@@ -0,0 +1,10 @@
+namespace EndUsersDomain;
+
+public enum RolesAndFeaturesUseCase
+{
+    CreatingMachine,
+    CreatingPerson,
+    CreatingOrg,
+    InvitingMemberToOrg,
+    InvitingMachineToCreatorOrg
+}
\ No newline at end of file
diff --git a/src/EndUsersInfrastructure.IntegrationTests/InvitationsApiSpec.cs b/src/EndUsersInfrastructure.IntegrationTests/InvitationsApiSpec.cs
index 044fa8c5..6ccb5d32 100644
--- a/src/EndUsersInfrastructure.IntegrationTests/InvitationsApiSpec.cs
+++ b/src/EndUsersInfrastructure.IntegrationTests/InvitationsApiSpec.cs
@@ -74,7 +74,7 @@ await Api.PostAsync(new InviteGuestRequest
     }
 
     [Fact]
-    public async Task WhenInviteUserAsGuestAndAlreadyRegistered_ThenReturnsError()
+    public async Task WhenInviteUserAsGuestAndAlreadyRegistered_ThenDoesNothing()
     {
         var login = await LoginUserAsync();
         var emailAddress = CreateRandomEmailAddress();
@@ -95,7 +95,9 @@ await Api.PostAsync(new InviteGuestRequest
             Email = emailAddress
         }, req => req.SetJWTBearerToken(login.AccessToken));
 
-        result.StatusCode.Should().Be(HttpStatusCode.Conflict);
+        result.Content.Value.Invitation!.EmailAddress.Should().Be(emailAddress);
+        result.Content.Value.Invitation!.FirstName.Should().Be("afirstname");
+        result.Content.Value.Invitation!.LastName.Should().Be("alastname");
         _notificationService.LastGuestInvitationEmailRecipient.Should().BeNull();
     }
 
diff --git a/src/EndUsersInfrastructure/ApplicationServices/EndUsersInProcessServiceClient.cs b/src/EndUsersInfrastructure/ApplicationServices/EndUsersInProcessServiceClient.cs
index c585dee1..476013cf 100644
--- a/src/EndUsersInfrastructure/ApplicationServices/EndUsersInProcessServiceClient.cs
+++ b/src/EndUsersInfrastructure/ApplicationServices/EndUsersInProcessServiceClient.cs
@@ -13,10 +13,13 @@ namespace EndUsersInfrastructure.ApplicationServices;
 public class EndUsersInProcessServiceClient : IEndUsersService
 {
     private readonly IEndUsersApplication _endUsersApplication;
+    private readonly IInvitationsApplication _invitationsApplication;
 
-    public EndUsersInProcessServiceClient(IEndUsersApplication endUsersApplication)
+    public EndUsersInProcessServiceClient(IEndUsersApplication endUsersApplication,
+        IInvitationsApplication invitationsApplication)
     {
         _endUsersApplication = endUsersApplication;
+        _invitationsApplication = invitationsApplication;
     }
 
     public async Task<Result<Membership, Error>> CreateMembershipForCallerPrivateAsync(ICallerContext caller,
@@ -39,6 +42,22 @@ public async Task<Result<EndUserWithMemberships, Error>> GetMembershipsPrivateAs
         return await _endUsersApplication.GetMembershipsAsync(caller, id, cancellationToken);
     }
 
+    public async Task<Result<Membership, Error>> InviteMemberToOrganizationPrivateAsync(ICallerContext caller,
+        string organizationId, string? userId, string? emailAddress,
+        CancellationToken cancellationToken)
+    {
+        return await _invitationsApplication.InviteMemberToOrganizationAsync(caller, organizationId, userId,
+            emailAddress, cancellationToken);
+    }
+
+    public async Task<Result<SearchResults<MembershipWithUserProfile>, Error>> ListMembershipsForOrganizationAsync(
+        ICallerContext caller, string organizationId, SearchOptions searchOptions,
+        GetOptions getOptions, CancellationToken cancellationToken)
+    {
+        return await _endUsersApplication.ListMembershipsForOrganizationAsync(caller, organizationId, searchOptions,
+            getOptions, cancellationToken);
+    }
+
     public async Task<Result<RegisteredEndUser, Error>> RegisterPersonPrivateAsync(ICallerContext caller,
         string? invitationToken, string emailAddress, string firstName, string? lastName, string? timezone,
         string? countryCode, bool termsAndConditionsAccepted, CancellationToken cancellationToken)
diff --git a/src/EndUsersInfrastructure/Persistence/EndUserRepository.cs b/src/EndUsersInfrastructure/Persistence/EndUserRepository.cs
index e1206c77..0931c3ac 100644
--- a/src/EndUsersInfrastructure/Persistence/EndUserRepository.cs
+++ b/src/EndUsersInfrastructure/Persistence/EndUserRepository.cs
@@ -1,6 +1,7 @@
+using Application.Interfaces;
+using Application.Persistence.Common.Extensions;
 using Application.Persistence.Interfaces;
 using Common;
-using Common.Extensions;
 using Domain.Common.ValueObjects;
 using Domain.Interfaces;
 using EndUsersApplication.Persistence;
@@ -8,11 +9,15 @@
 using EndUsersDomain;
 using Infrastructure.Persistence.Common;
 using Infrastructure.Persistence.Interfaces;
+using QueryAny;
+using EndUser = EndUsersApplication.Persistence.ReadModels.EndUser;
+using Tasks = Common.Extensions.Tasks;
 
 namespace EndUsersInfrastructure.Persistence;
 
 public class EndUserRepository : IEndUserRepository
 {
+    private readonly ISnapshottingQueryStore<MembershipJoinInvitation> _membershipUserQueries;
     private readonly ISnapshottingQueryStore<EndUser> _userQueries;
     private readonly IEventSourcingDddCommandStore<EndUserRoot> _users;
 
@@ -20,6 +25,7 @@ public EndUserRepository(IRecorder recorder, IDomainFactory domainFactory,
         IEventSourcingDddCommandStore<EndUserRoot> usersStore, IDataStore store)
     {
         _userQueries = new SnapshottingQueryStore<EndUser>(recorder, domainFactory, store);
+        _membershipUserQueries = new SnapshottingQueryStore<MembershipJoinInvitation>(recorder, domainFactory, store);
         _users = usersStore;
     }
 
@@ -27,6 +33,7 @@ public async Task<Result<Error>> DestroyAllAsync(CancellationToken cancellationT
     {
         return await Tasks.WhenAllAsync(
             _userQueries.DestroyAllAsync(cancellationToken),
+            _membershipUserQueries.DestroyAllAsync(cancellationToken),
             _users.DestroyAllAsync(cancellationToken));
     }
 
@@ -51,4 +58,31 @@ public async Task<Result<EndUserRoot, Error>> SaveAsync(EndUserRoot user, Cancel
 
         return user;
     }
+
+    public async Task<Result<List<MembershipJoinInvitation>, Error>> SearchAllMembershipsByOrganizationAsync(
+        Identifier organizationId, SearchOptions searchOptions, CancellationToken cancellationToken)
+    {
+        var query = Query.From<MembershipJoinInvitation>()
+            .Join<Invitation, string>(mje => mje.UserId, inv => inv.Id)
+            .Where<string>(mje => mje.OrganizationId, ConditionOperator.EqualTo, organizationId)
+            .Select(mje => mje.UserId)
+            .Select(mje => mje.Roles)
+            .Select(mje => mje.Features)
+            .Select(mje => mje.OrganizationId)
+            .Select(mje => mje.IsDefault)
+            .Select(mje => mje.LastPersistedAtUtc)
+            .SelectFromJoin<Invitation, string>(mje => mje.InvitedEmailAddress, inv => inv.InvitedEmailAddress)
+            .SelectFromJoin<Invitation, string>(mje => mje.Status, inv => inv.Status)
+            .OrderBy(mje => mje.LastPersistedAtUtc)
+            .WithSearchOptions(searchOptions);
+
+        var queried = await _membershipUserQueries.QueryAsync(query, cancellationToken: cancellationToken);
+        if (!queried.IsSuccessful)
+        {
+            return queried.Error;
+        }
+
+        var memberships = queried.Value.Results;
+        return memberships;
+    }
 }
\ No newline at end of file
diff --git a/src/IdentityApplication.UnitTests/PasswordCredentialsApplicationSpec.cs b/src/IdentityApplication.UnitTests/PasswordCredentialsApplicationSpec.cs
index 79433d1e..1a278cff 100644
--- a/src/IdentityApplication.UnitTests/PasswordCredentialsApplicationSpec.cs
+++ b/src/IdentityApplication.UnitTests/PasswordCredentialsApplicationSpec.cs
@@ -322,7 +322,7 @@ public async Task WhenRegisterPersonAsyncAndNotExists_ThenCreatesAndSendsConfirm
             {
                 Id = "anid",
                 UserId = "auserid",
-                Type = UserProfileType.Person,
+                Classification = UserProfileClassification.Person,
                 Name = new PersonName
                 {
                     FirstName = "aname"
diff --git a/src/IdentityInfrastructure.UnitTests/ApplicationServices/JWTTokensServiceSpec.cs b/src/IdentityInfrastructure.UnitTests/ApplicationServices/JWTTokensServiceSpec.cs
index a77f6d53..a825329d 100644
--- a/src/IdentityInfrastructure.UnitTests/ApplicationServices/JWTTokensServiceSpec.cs
+++ b/src/IdentityInfrastructure.UnitTests/ApplicationServices/JWTTokensServiceSpec.cs
@@ -45,16 +45,17 @@ public async Task WhenIssueTokensAsync_ThenReturnsTokens()
             Id = "anid",
             Roles = new List<string> { PlatformRoles.Standard.Name },
             Features = new List<string> { PlatformFeatures.Basic.Name },
-            Memberships = new List<Membership>
-            {
-                new()
+            Memberships =
+            [
+                new Membership
                 {
                     Id = "amembershipid",
+                    UserId = "auserid",
                     OrganizationId = "anorganizationid",
                     Roles = new List<string> { TenantRoles.Member.Name },
                     Features = new List<string> { TenantFeatures.Basic.Name }
                 }
-            }
+            ]
         };
 
         var result = await _service.IssueTokensAsync(user);
diff --git a/src/Infrastructure.Web.Api.Interfaces/ITenantedRequest.cs b/src/Infrastructure.Web.Api.Interfaces/ITenantedRequest.cs
index f9eed5b7..9635ea7e 100644
--- a/src/Infrastructure.Web.Api.Interfaces/ITenantedRequest.cs
+++ b/src/Infrastructure.Web.Api.Interfaces/ITenantedRequest.cs
@@ -1,7 +1,7 @@
 namespace Infrastructure.Web.Api.Interfaces;
 
 /// <summary>
-///     Defines the request for a specific Tenant
+///     Defines a request for a specific tenant
 /// </summary>
 public interface ITenantedRequest
 {
diff --git a/src/Infrastructure.Web.Api.Operations.Shared/Organizations/GetOrganizationRequest.cs b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/GetOrganizationRequest.cs
index ece4291b..937af194 100644
--- a/src/Infrastructure.Web.Api.Operations.Shared/Organizations/GetOrganizationRequest.cs
+++ b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/GetOrganizationRequest.cs
@@ -6,5 +6,5 @@ namespace Infrastructure.Web.Api.Operations.Shared.Organizations;
 [Authorize(Roles.Platform_Standard)]
 public class GetOrganizationRequest : UnTenantedRequest<GetOrganizationResponse>, IUnTenantedOrganizationRequest
 {
-    public required string Id { get; set; }
+    public string? Id { get; set; }
 }
\ No newline at end of file
diff --git a/src/Infrastructure.Web.Api.Operations.Shared/Organizations/InviteMemberToOrganizationRequest.cs b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/InviteMemberToOrganizationRequest.cs
new file mode 100644
index 00000000..f5ecbf00
--- /dev/null
+++ b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/InviteMemberToOrganizationRequest.cs
@@ -0,0 +1,15 @@
+using Infrastructure.Web.Api.Interfaces;
+
+namespace Infrastructure.Web.Api.Operations.Shared.Organizations;
+
+[Route("/organizations/{Id}/members", ServiceOperation.Post, AccessType.Token)]
+[Authorize(Roles.Tenant_Owner, Features.Tenant_Basic)]
+public class InviteMemberToOrganizationRequest : UnTenantedRequest<InviteMemberToOrganizationResponse>,
+    IUnTenantedOrganizationRequest
+{
+    public string? Email { get; set; }
+
+    public string? UserId { get; set; }
+
+    public string? Id { get; set; }
+}
\ No newline at end of file
diff --git a/src/Infrastructure.Web.Api.Operations.Shared/Organizations/InviteMemberToOrganizationResponse.cs b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/InviteMemberToOrganizationResponse.cs
new file mode 100644
index 00000000..a151898d
--- /dev/null
+++ b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/InviteMemberToOrganizationResponse.cs
@@ -0,0 +1,9 @@
+using Application.Resources.Shared;
+using Infrastructure.Web.Api.Interfaces;
+
+namespace Infrastructure.Web.Api.Operations.Shared.Organizations;
+
+public class InviteMemberToOrganizationResponse : IWebResponse
+{
+    public Organization? Organization { get; set; }
+}
\ No newline at end of file
diff --git a/src/Infrastructure.Web.Api.Operations.Shared/Organizations/ListMembersForOrganizationRequest.cs b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/ListMembersForOrganizationRequest.cs
new file mode 100644
index 00000000..3c3c46c7
--- /dev/null
+++ b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/ListMembersForOrganizationRequest.cs
@@ -0,0 +1,11 @@
+using Infrastructure.Web.Api.Interfaces;
+
+namespace Infrastructure.Web.Api.Operations.Shared.Organizations;
+
+[Route("/organizations/{Id}/members", ServiceOperation.Search, AccessType.Token)]
+[Authorize(Roles.Tenant_Member, Features.Tenant_Basic)]
+public class ListMembersForOrganizationRequest : UnTenantedSearchRequest<ListMembersForOrganizationResponse>,
+    IUnTenantedOrganizationRequest
+{
+    public string? Id { get; set; }
+}
\ No newline at end of file
diff --git a/src/Infrastructure.Web.Api.Operations.Shared/Organizations/ListMembersForOrganizationResponse.cs b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/ListMembersForOrganizationResponse.cs
new file mode 100644
index 00000000..801c6eeb
--- /dev/null
+++ b/src/Infrastructure.Web.Api.Operations.Shared/Organizations/ListMembersForOrganizationResponse.cs
@@ -0,0 +1,9 @@
+using Application.Resources.Shared;
+using Infrastructure.Web.Api.Interfaces;
+
+namespace Infrastructure.Web.Api.Operations.Shared.Organizations;
+
+public class ListMembersForOrganizationResponse : SearchResponse
+{
+    public List<OrganizationMember>? Members { get; set; }
+}
\ No newline at end of file
diff --git a/src/Infrastructure.Web.Hosting.Common.UnitTests/Pipeline/MultiTenancyMiddlewareSpec.cs b/src/Infrastructure.Web.Hosting.Common.UnitTests/Pipeline/MultiTenancyMiddlewareSpec.cs
index 05395e66..b79944fb 100644
--- a/src/Infrastructure.Web.Hosting.Common.UnitTests/Pipeline/MultiTenancyMiddlewareSpec.cs
+++ b/src/Infrastructure.Web.Hosting.Common.UnitTests/Pipeline/MultiTenancyMiddlewareSpec.cs
@@ -431,14 +431,15 @@ public async Task WhenInvokeAndUnRequiredTenantIdAndIsAMember_ThenSetsTenantAndC
                 .ReturnsAsync(new EndUserWithMemberships
                 {
                     Id = "auserid",
-                    Memberships = new List<Membership>
-                    {
-                        new()
+                    Memberships =
+                    [
+                        new Membership
                         {
                             Id = "amembershipid",
+                            UserId = "auserid",
                             OrganizationId = "atenantid"
                         }
-                    }
+                    ]
                 });
 
             await _middleware.InvokeAsync(context, _tenancyContext.Object, _callerContextFactory.Object,
@@ -490,14 +491,15 @@ public async Task WhenInvokeAndNoRequiredTenantIdButNoDefaultOrganization_ThenRe
                 .ReturnsAsync(new EndUserWithMemberships
                 {
                     Id = "auserid",
-                    Memberships = new List<Membership>
-                    {
-                        new()
+                    Memberships =
+                    [
+                        new Membership
                         {
                             Id = "amembershipid",
+                            UserId = "auserid",
                             OrganizationId = "atenantid"
                         }
-                    }
+                    ]
                 });
 
             await _middleware.InvokeAsync(context, _tenancyContext.Object, _callerContextFactory.Object,
@@ -527,15 +529,16 @@ public async Task WhenInvokeAndNoRequiredTenantIdButHasDefaultOrganization_ThenS
                 .ReturnsAsync(new EndUserWithMemberships
                 {
                     Id = "auserid",
-                    Memberships = new List<Membership>
-                    {
-                        new()
+                    Memberships =
+                    [
+                        new Membership
                         {
                             Id = "amembershipid",
+                            UserId = "auserid",
                             IsDefault = true,
                             OrganizationId = "adefaultorganizationid"
                         }
-                    }
+                    ]
                 });
 
             await _middleware.InvokeAsync(context, _tenancyContext.Object, _callerContextFactory.Object,
@@ -588,14 +591,15 @@ public async Task WhenInvokeAndRequiredTenantIdAndIsAMember_ThenSetsTenantAndCon
                 .ReturnsAsync(new EndUserWithMemberships
                 {
                     Id = "auserid",
-                    Memberships = new List<Membership>
-                    {
-                        new()
+                    Memberships =
+                    [
+                        new Membership
                         {
                             Id = "amembershipid",
+                            UserId = "auserid",
                             OrganizationId = "atenantid"
                         }
-                    }
+                    ]
                 });
 
             await _middleware.InvokeAsync(context, _tenancyContext.Object, _callerContextFactory.Object,
diff --git a/src/IntegrationTesting.WebApi.Common/WebApiSpec.cs b/src/IntegrationTesting.WebApi.Common/WebApiSpec.cs
index d4d981de..3cd6df7c 100644
--- a/src/IntegrationTesting.WebApi.Common/WebApiSpec.cs
+++ b/src/IntegrationTesting.WebApi.Common/WebApiSpec.cs
@@ -188,13 +188,12 @@ protected async Task<LoginDetails> LoginUserAsync(LoginUser who = LoginUser.Pers
 
         var person = await RegisterUserAsync(emailAddress, firstName);
 
-        return await ReAuthenticateUserAsync(person.Credential!.User, who);
+        return await ReAuthenticateUserAsync(person.Credential!.User);
     }
 
-    protected async Task<LoginDetails> ReAuthenticateUserAsync(RegisteredEndUser user,
-        LoginUser who = LoginUser.PersonA)
+    protected async Task<LoginDetails> ReAuthenticateUserAsync(RegisteredEndUser user)
     {
-        var emailAddress = GetEmailForPerson(who);
+        var emailAddress = user.Profile!.EmailAddress!;
 
         var login = await Api.PostAsync(new AuthenticatePasswordRequest
         {
diff --git a/src/OrganizationsApplication.UnitTests/OrganizationsApplicationSpec.cs b/src/OrganizationsApplication.UnitTests/OrganizationsApplicationSpec.cs
index 76969144..e1ebb26c 100644
--- a/src/OrganizationsApplication.UnitTests/OrganizationsApplicationSpec.cs
+++ b/src/OrganizationsApplication.UnitTests/OrganizationsApplicationSpec.cs
@@ -5,6 +5,7 @@
 using Common;
 using Domain.Common.Identity;
 using Domain.Common.ValueObjects;
+using Domain.Interfaces.Authorization;
 using Domain.Interfaces.Entities;
 using Domain.Interfaces.Services;
 using FluentAssertions;
@@ -90,6 +91,7 @@ public async Task WhenCreateSharedOrganizationAsync_ThenReturnsSharedOrganizatio
             .ReturnsAsync(new Membership
             {
                 Id = "amembershipid",
+                UserId = "auserid",
                 OrganizationId = "anorganizationid",
                 IsDefault = false
             });
@@ -196,7 +198,7 @@ public async Task WhenChangeSettingsAndNotExists_ThenReturnsError()
     public async Task WhenChangeSettings_ThenReturnsSettings()
     {
         var org = OrganizationRoot.Create(_recorder.Object, _idFactory.Object, _tenantSettingService.Object,
-            Ownership.Personal, "auserid".ToId(), DisplayName.Create("aname").Value).Value;
+            Ownership.Shared, "auserid".ToId(), DisplayName.Create("aname").Value).Value;
         org.CreateSettings(Settings.Create(new Dictionary<string, Setting>
         {
             { "aname1", Setting.Create("anoldvalue", true).Value },
@@ -216,7 +218,7 @@ public async Task WhenChangeSettings_ThenReturnsSettings()
         result.Should().BeSuccess();
         _repository.Verify(rep => rep.SaveAsync(It.Is<OrganizationRoot>(o =>
             o.Name == "aname"
-            && o.Ownership == Ownership.Personal
+            && o.Ownership == Ownership.Shared
             && o.CreatedById == "auserid"
             && o.Settings.Properties.Count == 4
             && o.Settings.Properties["aname1"].Value.As<string>() == "anewvalue"
@@ -228,4 +230,176 @@ public async Task WhenChangeSettings_ThenReturnsSettings()
                 tss.CreateForTenantAsync(It.IsAny<ICallerContext>(), It.IsAny<string>(), It.IsAny<CancellationToken>()),
             Times.Never);
     }
+
+    [Fact]
+    public async Task WhenInviteMemberToOrganizationAsyncAndNotExist_ThenReturnsError()
+    {
+        _repository.Setup(s =>
+                s.LoadAsync(It.IsAny<Identifier>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(Error.EntityNotFound());
+
+        var result = await _application.InviteMemberToOrganizationAsync(_caller.Object, "anorganizationid",
+            "auserid", null, CancellationToken.None);
+
+        result.Should().BeError(ErrorCode.EntityNotFound);
+    }
+
+    [Fact]
+    public async Task WhenInviteMemberToOrganizationAsync_ThenInvites()
+    {
+        _caller.Setup(cc => cc.Roles)
+            .Returns(new ICallerContext.CallerRoles(Array.Empty<RoleLevel>(), new[] { TenantRoles.Owner }));
+        var org = OrganizationRoot.Create(_recorder.Object, _idFactory.Object, _tenantSettingService.Object,
+            Ownership.Shared, "auserid".ToId(), DisplayName.Create("aname").Value).Value;
+        _repository.Setup(s =>
+                s.LoadAsync(It.IsAny<Identifier>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(org);
+        _endUsersService.Setup(eus =>
+                eus.InviteMemberToOrganizationPrivateAsync(It.IsAny<ICallerContext>(), It.IsAny<string>(),
+                    It.IsAny<string>(),
+                    It.IsAny<string>(),
+                    It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new Membership
+            {
+                Id = "amembershipid",
+                UserId = "auserid",
+                OrganizationId = "anorganizationid",
+                IsDefault = false
+            });
+
+        var result = await _application.InviteMemberToOrganizationAsync(_caller.Object, "anorganizationid",
+            "auserid", null, CancellationToken.None);
+
+        result.Should().BeSuccess();
+        result.Value.Name.Should().Be("aname");
+        result.Value.CreatedById.Should().Be("auserid");
+        result.Value.Ownership.Should().Be(OrganizationOwnership.Shared);
+        _endUsersService.Verify(eus =>
+            eus.InviteMemberToOrganizationPrivateAsync(_caller.Object, "anorganizationid", "auserid", null,
+                CancellationToken.None));
+    }
+
+    [Fact]
+    public async Task WhenListMembersForOrganizationAsyncAndNotExist_ThenReturnsError()
+    {
+        _repository.Setup(s =>
+                s.LoadAsync(It.IsAny<Identifier>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(Error.EntityNotFound());
+
+        var result = await _application.ListMembersForOrganizationAsync(_caller.Object, "anorganizationid",
+            new SearchOptions(), new GetOptions(), CancellationToken.None);
+
+        result.Should().BeError(ErrorCode.EntityNotFound);
+    }
+
+    [Fact]
+    public async Task WhenListMembersForOrganizationAsyncWithUnregisteredUser_ThenReturnsMemberships()
+    {
+        var org = OrganizationRoot.Create(_recorder.Object, _idFactory.Object, _tenantSettingService.Object,
+            Ownership.Shared, "auserid".ToId(), DisplayName.Create("aname").Value).Value;
+        _repository.Setup(s =>
+                s.LoadAsync(It.IsAny<Identifier>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(org);
+        _endUsersService.Setup(eus => eus.ListMembershipsForOrganizationAsync(It.IsAny<ICallerContext>(),
+                It.IsAny<string>(),
+                It.IsAny<SearchOptions>(), It.IsAny<GetOptions>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new SearchResults<MembershipWithUserProfile>
+            {
+                Results =
+                [
+                    new MembershipWithUserProfile
+                    {
+                        Id = "amembershipid",
+                        UserId = "auserid",
+                        Status = EndUserStatus.Unregistered,
+                        Roles = ["arole1", "arole2", "arole3"],
+                        Features = ["afeature1", "afeature2", "afeature3"],
+                        Profile = new UserProfile
+                        {
+                            Id = "aprofileid",
+                            UserId = "auserid",
+                            EmailAddress = "anemailaddress",
+                            Name = new PersonName
+                            {
+                                FirstName = "anemailaddress"
+                            },
+                            DisplayName = "anemailaddress"
+                        },
+                        OrganizationId = "anorganizationid",
+                        IsDefault = false
+                    }
+                ]
+            });
+
+        var result = await _application.ListMembersForOrganizationAsync(_caller.Object, "anorganizationid",
+            new SearchOptions(), new GetOptions(), CancellationToken.None);
+
+        result.Should().BeSuccess();
+        result.Value.Results.Count.Should().Be(1);
+        result.Value.Results[0].Id.Should().Be("amembershipid");
+        result.Value.Results[0].UserId.Should().Be("auserid");
+        result.Value.Results[0].IsRegistered.Should().BeFalse();
+        result.Value.Results[0].IsOwner.Should().BeFalse();
+        result.Value.Results[0].EmailAddress.Should().Be("anemailaddress");
+        result.Value.Results[0].Name.FirstName.Should().Be("anemailaddress");
+        result.Value.Results[0].Name.LastName.Should().BeNull();
+        result.Value.Results[0].Roles.Should().ContainInOrder("arole1", "arole2", "arole3");
+        result.Value.Results[0].Features.Should().ContainInOrder("afeature1", "afeature2", "afeature3");
+    }
+
+    [Fact]
+    public async Task WhenListMembersForOrganizationAsyncWithRegisteredUsers_ThenReturnsMemberships()
+    {
+        var org = OrganizationRoot.Create(_recorder.Object, _idFactory.Object, _tenantSettingService.Object,
+            Ownership.Shared, "auserid".ToId(), DisplayName.Create("aname").Value).Value;
+        _repository.Setup(s =>
+                s.LoadAsync(It.IsAny<Identifier>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(org);
+        _endUsersService.Setup(eus => eus.ListMembershipsForOrganizationAsync(It.IsAny<ICallerContext>(),
+                It.IsAny<string>(),
+                It.IsAny<SearchOptions>(), It.IsAny<GetOptions>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new SearchResults<MembershipWithUserProfile>
+            {
+                Results =
+                [
+                    new MembershipWithUserProfile
+                    {
+                        Id = "amembershipid",
+                        UserId = "auserid",
+                        Status = EndUserStatus.Registered,
+                        Roles = ["arole1", "arole2", "arole3"],
+                        Features = ["afeature1", "afeature2", "afeature3"],
+                        OrganizationId = "anorganizationid",
+                        Profile = new UserProfile
+                        {
+                            Id = "aprofileid",
+                            UserId = "auserid",
+                            EmailAddress = "anemailaddress",
+                            Name = new PersonName
+                            {
+                                FirstName = "afirstname",
+                                LastName = "alastname"
+                            },
+                            DisplayName = "adisplayname"
+                        },
+                        IsDefault = false
+                    }
+                ]
+            });
+
+        var result = await _application.ListMembersForOrganizationAsync(_caller.Object, "anorganizationid",
+            new SearchOptions(), new GetOptions(), CancellationToken.None);
+
+        result.Should().BeSuccess();
+        result.Value.Results.Count.Should().Be(1);
+        result.Value.Results[0].Id.Should().Be("amembershipid");
+        result.Value.Results[0].UserId.Should().Be("auserid");
+        result.Value.Results[0].IsRegistered.Should().BeTrue();
+        result.Value.Results[0].IsOwner.Should().BeFalse();
+        result.Value.Results[0].EmailAddress.Should().Be("anemailaddress");
+        result.Value.Results[0].Name.FirstName.Should().Be("afirstname");
+        result.Value.Results[0].Name.LastName.Should().Be("alastname");
+        result.Value.Results[0].Roles.Should().ContainInOrder("arole1", "arole2", "arole3");
+        result.Value.Results[0].Features.Should().ContainInOrder("afeature1", "afeature2", "afeature3");
+    }
 }
\ No newline at end of file
diff --git a/src/OrganizationsApplication/IOrganizationsApplication.cs b/src/OrganizationsApplication/IOrganizationsApplication.cs
index 4c1560fe..382f0eb5 100644
--- a/src/OrganizationsApplication/IOrganizationsApplication.cs
+++ b/src/OrganizationsApplication/IOrganizationsApplication.cs
@@ -26,4 +26,10 @@ Task<Result<OrganizationWithSettings, Error>> GetOrganizationSettingsAsync(ICall
 
     Task<Result<TenantSettings, Error>> GetSettingsAsync(ICallerContext caller, string id,
         CancellationToken cancellationToken);
+
+    Task<Result<Organization, Error>> InviteMemberToOrganizationAsync(ICallerContext caller, string id, string? userId,
+        string? emailAddress, CancellationToken cancellationToken);
+
+    Task<Result<SearchResults<OrganizationMember>, Error>> ListMembersForOrganizationAsync(ICallerContext caller,
+        string? id, SearchOptions searchOptions, GetOptions getOptions, CancellationToken cancellationToken);
 }
\ No newline at end of file
diff --git a/src/OrganizationsApplication/OrganizationsApplication.cs b/src/OrganizationsApplication/OrganizationsApplication.cs
index ec8606da..a94ceb16 100644
--- a/src/OrganizationsApplication/OrganizationsApplication.cs
+++ b/src/OrganizationsApplication/OrganizationsApplication.cs
@@ -7,7 +7,9 @@
 using Common.Extensions;
 using Domain.Common.Identity;
 using Domain.Common.ValueObjects;
+using Domain.Interfaces.Authorization;
 using Domain.Interfaces.Services;
+using Domain.Shared;
 using OrganizationsApplication.Persistence;
 using OrganizationsDomain;
 
@@ -189,10 +191,92 @@ public async Task<Result<TenantSettings, Error>> GetSettingsAsync(ICallerContext
 
         return settings.ToSettings();
     }
+
+    public async Task<Result<Organization, Error>> InviteMemberToOrganizationAsync(ICallerContext caller, string id,
+        string? userId, string? emailAddress, CancellationToken cancellationToken)
+    {
+        var retrieved = await _repository.LoadAsync(id.ToId(), cancellationToken);
+        if (!retrieved.IsSuccessful)
+        {
+            return retrieved.Error;
+        }
+
+        var organization = retrieved.Value;
+        var inviterRoles = Roles.Create(caller.Roles.Tenant);
+        if (!inviterRoles.IsSuccessful)
+        {
+            return inviterRoles.Error;
+        }
+
+        Identifier? addedUserId = null;
+        var added = await organization.AddMembershipAsync(caller.ToCallerId(), inviterRoles.Value, async () =>
+        {
+            var membership =
+                await _endUsersService.InviteMemberToOrganizationPrivateAsync(caller, id, userId, emailAddress,
+                    cancellationToken);
+            if (!membership.IsSuccessful)
+            {
+                return membership.Error;
+            }
+
+            addedUserId = membership.Value.UserId.ToId();
+            return Result.Ok;
+        });
+        if (!added.IsSuccessful)
+        {
+            return added.Error;
+        }
+
+        _recorder.TraceInformation(caller.ToCall(), "Organization {Id} has invited {UserId} to be a member",
+            organization.Id, addedUserId!);
+
+        return organization.ToOrganization();
+    }
+
+    public async Task<Result<SearchResults<OrganizationMember>, Error>> ListMembersForOrganizationAsync(
+        ICallerContext caller, string? id, SearchOptions searchOptions,
+        GetOptions getOptions, CancellationToken cancellationToken)
+    {
+        var retrieved = await _repository.LoadAsync(id.ToId(), cancellationToken);
+        if (!retrieved.IsSuccessful)
+        {
+            return retrieved.Error;
+        }
+
+        var organization = retrieved.Value;
+        var memberships =
+            await _endUsersService.ListMembershipsForOrganizationAsync(caller, organization.Id, searchOptions,
+                getOptions, cancellationToken);
+        if (!memberships.IsSuccessful)
+        {
+            return memberships.Error;
+        }
+
+        return searchOptions.ApplyWithMetadata(memberships.Value.Results.ConvertAll(x => x.ToMember()));
+    }
 }
 
 internal static class OrganizationConversionExtensions
 {
+    public static OrganizationMember ToMember(this MembershipWithUserProfile membership)
+    {
+        var dto = new OrganizationMember
+        {
+            Id = membership.Id,
+            UserId = membership.UserId,
+            IsDefault = membership.IsDefault,
+            IsRegistered = membership.Status == EndUserStatus.Registered,
+            IsOwner = membership.Roles.Contains(TenantRoles.Owner.Name),
+            Roles = membership.Roles,
+            Features = membership.Features,
+            EmailAddress = membership.Profile.EmailAddress,
+            Name = membership.Profile.Name,
+            Classification = membership.Profile.Classification
+        };
+
+        return dto;
+    }
+
     public static Organization ToOrganization(this OrganizationRoot organization)
     {
         return new Organization
diff --git a/src/OrganizationsApplication/OrganizationsApplication.csproj b/src/OrganizationsApplication/OrganizationsApplication.csproj
index f1e837b2..1f42228f 100644
--- a/src/OrganizationsApplication/OrganizationsApplication.csproj
+++ b/src/OrganizationsApplication/OrganizationsApplication.csproj
@@ -11,6 +11,7 @@
         <ProjectReference Include="..\Application.Persistence.Interfaces\Application.Persistence.Interfaces.csproj" />
         <ProjectReference Include="..\Application.Resources.Shared\Application.Resources.Shared.csproj" />
         <ProjectReference Include="..\Application.Services.Shared\Application.Services.Shared.csproj" />
+        <ProjectReference Include="..\Domain.Shared\Domain.Shared.csproj" />
         <ProjectReference Include="..\OrganizationsDomain\OrganizationsDomain.csproj" />
     </ItemGroup>
 
diff --git a/src/OrganizationsDomain/OrganizationRoot.cs b/src/OrganizationsDomain/OrganizationRoot.cs
index fe573b0f..20661f94 100644
--- a/src/OrganizationsDomain/OrganizationRoot.cs
+++ b/src/OrganizationsDomain/OrganizationRoot.cs
@@ -3,12 +3,16 @@
 using Domain.Common.Identity;
 using Domain.Common.ValueObjects;
 using Domain.Interfaces;
+using Domain.Interfaces.Authorization;
 using Domain.Interfaces.Entities;
 using Domain.Interfaces.Services;
 using Domain.Interfaces.ValueObjects;
+using Domain.Shared;
 
 namespace OrganizationsDomain;
 
+public delegate Task<Result<Error>> Callback();
+
 public sealed class OrganizationRoot : AggregateRootBase
 {
     private readonly ITenantSettingService _tenantSettingService;
@@ -126,6 +130,16 @@ protected override Result<Error> OnStateChanged(IDomainEvent @event, bool isReco
         }
     }
 
+    public async Task<Result<Error>> AddMembershipAsync(Identifier inviterId, Roles inviterRoles, Callback onPermitted)
+    {
+        if (!IsOwner(inviterRoles))
+        {
+            return Error.RoleViolation(Resources.OrganizationRoot_AddMembership_NotOrgOwner);
+        }
+
+        return await onPermitted();
+    }
+
     public Result<Error> CreateSettings(Settings settings)
     {
         foreach (var (key, value) in settings.Properties)
@@ -167,4 +181,9 @@ public Result<Error> UpdateSettings(Settings settings)
 
         return Result.Ok;
     }
+
+    private static bool IsOwner(Roles roles)
+    {
+        return roles.HasRole(TenantRoles.Owner);
+    }
 }
\ No newline at end of file
diff --git a/src/OrganizationsDomain/OrganizationsDomain.csproj b/src/OrganizationsDomain/OrganizationsDomain.csproj
index 98374b83..bf791e77 100644
--- a/src/OrganizationsDomain/OrganizationsDomain.csproj
+++ b/src/OrganizationsDomain/OrganizationsDomain.csproj
@@ -6,6 +6,7 @@
 
     <ItemGroup>
         <ProjectReference Include="..\Domain.Common\Domain.Common.csproj" />
+        <ProjectReference Include="..\Domain.Shared\Domain.Shared.csproj" />
     </ItemGroup>
 
     <ItemGroup>
diff --git a/src/OrganizationsDomain/Resources.Designer.cs b/src/OrganizationsDomain/Resources.Designer.cs
index 7fe9ae50..ee174d4c 100644
--- a/src/OrganizationsDomain/Resources.Designer.cs
+++ b/src/OrganizationsDomain/Resources.Designer.cs
@@ -68,6 +68,15 @@ internal static string OrganizationDisplayName_InvalidName {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to You must be an organization owner to perform this action.
+        /// </summary>
+        internal static string OrganizationRoot_AddMembership_NotOrgOwner {
+            get {
+                return ResourceManager.GetString("OrganizationRoot_AddMembership_NotOrgOwner", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to The data type of the value: &apos;{0}&apos; is unsupported.
         /// </summary>
diff --git a/src/OrganizationsDomain/Resources.resx b/src/OrganizationsDomain/Resources.resx
index 7ad336d3..478c517f 100644
--- a/src/OrganizationsDomain/Resources.resx
+++ b/src/OrganizationsDomain/Resources.resx
@@ -33,4 +33,7 @@
     <data name="Setting_InvalidValueType" xml:space="preserve">
         <value>The value type of the value: '{0}' is unsupported</value>
     </data>
+    <data name="OrganizationRoot_AddMembership_NotOrgOwner" xml:space="preserve">
+        <value>You must be an organization owner to perform this action</value>
+    </data>
 </root>
\ No newline at end of file
diff --git a/src/OrganizationsInfrastructure.IntegrationTests/OrganizationsApiSpec.cs b/src/OrganizationsInfrastructure.IntegrationTests/OrganizationsApiSpec.cs
index 54a540fb..118e50c6 100644
--- a/src/OrganizationsInfrastructure.IntegrationTests/OrganizationsApiSpec.cs
+++ b/src/OrganizationsInfrastructure.IntegrationTests/OrganizationsApiSpec.cs
@@ -1,7 +1,9 @@
 using ApiHost1;
 using Application.Resources.Shared;
+using Domain.Interfaces.Authorization;
 using FluentAssertions;
 using Infrastructure.Web.Api.Common.Extensions;
+using Infrastructure.Web.Api.Operations.Shared.Identities;
 using Infrastructure.Web.Api.Operations.Shared.Organizations;
 using IntegrationTesting.WebApi.Common;
 using Xunit;
@@ -12,13 +14,15 @@ namespace OrganizationsInfrastructure.IntegrationTests;
 [Collection("API")]
 public class OrganizationsApiSpec : WebApiSpec<Program>
 {
+    private static int _invitationCount;
+
     public OrganizationsApiSpec(WebApiSetup<Program> setup) : base(setup)
     {
         EmptyAllRepositories();
     }
 
     [Fact]
-    public async Task WhenGetDefaultOrganization_ThenReturnsOrganization()
+    public async Task WhenGetOrganization_ThenReturnsOrganization()
     {
         var login = await LoginUserAsync();
 
@@ -35,7 +39,7 @@ public async Task WhenGetDefaultOrganization_ThenReturnsOrganization()
     [Fact]
     public async Task WhenCreateOrganization_ThenReturnsOrganization()
     {
-        var login = await LoginUserAsync(LoginUser.Operator);
+        var login = await LoginUserAsync();
 
         var result = await Api.PostAsync(new CreateOrganizationRequest
         {
@@ -46,4 +50,85 @@ public async Task WhenCreateOrganization_ThenReturnsOrganization()
         result.Content.Value.Organization!.Name.Should().Be("anorganizationname");
         result.Content.Value.Organization!.Ownership.Should().Be(OrganizationOwnership.Shared);
     }
+
+    [Fact]
+    public async Task WhenInviteMembersToOrganization_ThenAddsMembers()
+    {
+        var loginA = await LoginUserAsync();
+        var loginB = await LoginUserAsync(LoginUser.PersonB);
+        var loginC = CreateRandomEmailAddress();
+
+        var organization = await Api.PostAsync(new CreateOrganizationRequest
+        {
+            Name = "anorganizationname"
+        }, req => req.SetJWTBearerToken(loginA.AccessToken));
+
+        loginA = await ReAuthenticateUserAsync(loginA.User);
+        var organizationId = organization.Content.Value.Organization!.Id;
+        await Api.PostAsync(new InviteMemberToOrganizationRequest
+        {
+            Id = organizationId,
+            Email = loginB.User.Profile!.EmailAddress
+        }, req => req.SetJWTBearerToken(loginA.AccessToken));
+
+        await Api.PostAsync(new InviteMemberToOrganizationRequest
+        {
+            Id = organizationId,
+            Email = loginC
+        }, req => req.SetJWTBearerToken(loginA.AccessToken));
+
+        var machine = await Api.PostAsync(new RegisterMachineRequest
+        {
+            Name = "amachinename"
+        }, req => req.SetJWTBearerToken(loginA.AccessToken));
+
+        var members = await Api.GetAsync(new ListMembersForOrganizationRequest
+        {
+            Id = organizationId,
+        }, req => req.SetJWTBearerToken(loginA.AccessToken));
+
+        members.Content.Value.Members!.Count.Should().Be(4);
+        members.Content.Value.Members[0].IsDefault.Should().BeTrue();
+        members.Content.Value.Members[0].IsOwner.Should().BeTrue();
+        members.Content.Value.Members[0].IsRegistered.Should().BeTrue();
+        members.Content.Value.Members[0].UserId.Should().Be(loginA.User.Id);
+        members.Content.Value.Members[0].EmailAddress.Should().Be(loginA.User.Profile!.EmailAddress);
+        members.Content.Value.Members[0].Name.FirstName.Should().Be("persona");
+        members.Content.Value.Members[0].Name.LastName.Should().Be("alastname");
+        members.Content.Value.Members[0].Classification.Should().Be(UserProfileClassification.Person);
+        members.Content.Value.Members[0].Roles.Should().ContainInOrder(TenantRoles.BillingAdmin.Name,
+            TenantRoles.Owner.Name, TenantRoles.Member.Name);
+        members.Content.Value.Members[1].IsDefault.Should().BeTrue();
+        members.Content.Value.Members[1].IsOwner.Should().BeFalse();
+        members.Content.Value.Members[1].IsRegistered.Should().BeTrue();
+        members.Content.Value.Members[1].UserId.Should().Be(loginB.User.Id);
+        members.Content.Value.Members[1].EmailAddress.Should().Be(loginB.User.Profile!.EmailAddress);
+        members.Content.Value.Members[1].Name.FirstName.Should().Be("personb");
+        members.Content.Value.Members[1].Name.LastName.Should().Be("alastname");
+        members.Content.Value.Members[1].Classification.Should().Be(UserProfileClassification.Person);
+        members.Content.Value.Members[1].Roles.Should().ContainSingle(role => role == TenantRoles.Member.Name);
+        members.Content.Value.Members[2].IsDefault.Should().BeTrue();
+        members.Content.Value.Members[2].IsOwner.Should().BeFalse();
+        members.Content.Value.Members[2].IsRegistered.Should().BeFalse();
+        members.Content.Value.Members[2].UserId.Should().NotBeNullOrEmpty();
+        members.Content.Value.Members[2].EmailAddress.Should().Be(loginC);
+        members.Content.Value.Members[2].Name.FirstName.Should().Be(loginC);
+        members.Content.Value.Members[2].Name.LastName.Should().BeNull();
+        members.Content.Value.Members[2].Classification.Should().Be(UserProfileClassification.Person);
+        members.Content.Value.Members[2].Roles.Should().ContainSingle(role => role == TenantRoles.Member.Name);
+        members.Content.Value.Members[3].IsDefault.Should().BeTrue();
+        members.Content.Value.Members[3].IsOwner.Should().BeFalse();
+        members.Content.Value.Members[3].IsRegistered.Should().BeTrue();
+        members.Content.Value.Members[3].UserId.Should().Be(machine.Content.Value.Machine!.Id);
+        members.Content.Value.Members[3].EmailAddress.Should().BeNull();
+        members.Content.Value.Members[3].Name.FirstName.Should().Be("amachinename");
+        members.Content.Value.Members[3].Name.LastName.Should().BeNull();
+        members.Content.Value.Members[3].Classification.Should().Be(UserProfileClassification.Machine);
+        members.Content.Value.Members[3].Roles.Should().ContainSingle(role => role == TenantRoles.Member.Name);
+    }
+
+    private static string CreateRandomEmailAddress()
+    {
+        return $"aninvitee{++_invitationCount}@company.com";
+    }
 }
\ No newline at end of file
diff --git a/src/OrganizationsInfrastructure.UnitTests/Api/Organizations/InviteMemberToOrganizationRequestValidatorSpec.cs b/src/OrganizationsInfrastructure.UnitTests/Api/Organizations/InviteMemberToOrganizationRequestValidatorSpec.cs
new file mode 100644
index 00000000..3713f88c
--- /dev/null
+++ b/src/OrganizationsInfrastructure.UnitTests/Api/Organizations/InviteMemberToOrganizationRequestValidatorSpec.cs
@@ -0,0 +1,77 @@
+using Domain.Common.Identity;
+using FluentAssertions;
+using FluentValidation;
+using Infrastructure.Web.Api.Operations.Shared.Organizations;
+using OrganizationsInfrastructure.Api.Organizations;
+using UnitTesting.Common.Validation;
+using Xunit;
+
+namespace OrganizationsInfrastructure.UnitTests.Api.Organizations;
+
+[Trait("Category", "Unit")]
+public class InviteMemberToOrganizationRequestValidatorSpec
+{
+    private readonly InviteMemberToOrganizationRequest _dto;
+    private readonly InviteMemberToOrganizationRequestValidator _validator;
+
+    public InviteMemberToOrganizationRequestValidatorSpec()
+    {
+        _validator = new InviteMemberToOrganizationRequestValidator(new FixedIdentifierFactory("anid"));
+        _dto = new InviteMemberToOrganizationRequest
+        {
+            Id = "anid",
+            UserId = "anid"
+        };
+    }
+
+    [Fact]
+    public void WhenAllProperties_ThenSucceeds()
+    {
+        _validator.ValidateAndThrow(_dto);
+    }
+
+    [Fact]
+    public void WhenUserIdAndEmailMissing_ThenThrows()
+    {
+        _dto.UserId = null;
+        _dto.Email = null;
+
+        _validator
+            .Invoking(x => x.ValidateAndThrow(_dto))
+            .Should().Throw<ValidationException>()
+            .WithMessageLike(Resources.InviteOrganizationMemberRequestValidator_MissingUserIdAndEmail);
+    }
+
+    [Fact]
+    public void WhenEmailIsInvalid_ThenThrows()
+    {
+        _dto.UserId = null;
+        _dto.Email = "notanemail";
+
+        _validator
+            .Invoking(x => x.ValidateAndThrow(_dto))
+            .Should().Throw<ValidationException>()
+            .WithMessageLike(Resources.InviteOrganizationMemberRequestValidator_InvalidUserEmail);
+    }
+
+    [Fact]
+    public void WhenEmailIsValid_ThenSucceeds()
+    {
+        _dto.UserId = null;
+        _dto.Email = "auser@company.com";
+
+        _validator.ValidateAndThrow(_dto);
+    }
+
+    [Fact]
+    public void WhenEmailAndUserIdIsValid_ThenSucceeds()
+    {
+        _dto.UserId = "anid";
+        _dto.Email = "auser@company.com";
+
+        _validator
+            .Invoking(x => x.ValidateAndThrow(_dto))
+            .Should().Throw<ValidationException>()
+            .WithMessageLike(Resources.InviteOrganizationMemberRequestValidator_BothUserIdAndEmail);
+    }
+}
\ No newline at end of file
diff --git a/src/OrganizationsInfrastructure/Api/Organizations/InviteMemberToOrganizationRequestValidator.cs b/src/OrganizationsInfrastructure/Api/Organizations/InviteMemberToOrganizationRequestValidator.cs
new file mode 100644
index 00000000..ad60aa13
--- /dev/null
+++ b/src/OrganizationsInfrastructure/Api/Organizations/InviteMemberToOrganizationRequestValidator.cs
@@ -0,0 +1,34 @@
+using Common.Extensions;
+using Domain.Common.Identity;
+using Domain.Interfaces.Validations;
+using FluentValidation;
+using Infrastructure.Web.Api.Common.Validation;
+using Infrastructure.Web.Api.Operations.Shared.Organizations;
+
+namespace OrganizationsInfrastructure.Api.Organizations;
+
+public class InviteMemberToOrganizationRequestValidator : AbstractValidator<InviteMemberToOrganizationRequest>
+{
+    public InviteMemberToOrganizationRequestValidator(IIdentifierFactory identifierFactory)
+    {
+        RuleFor(req => req.Id)
+            .IsEntityId(identifierFactory)
+            .WithMessage(CommonValidationResources.AnyValidator_InvalidId);
+        RuleFor(req => req.UserId)
+            .IsEntityId(identifierFactory)
+            .WithMessage(CommonValidationResources.AnyValidator_InvalidId)
+            .When(req => req.UserId.HasValue());
+        RuleFor(req => req.Email)
+            .IsEmailAddress()
+            .WithMessage(Resources.InviteOrganizationMemberRequestValidator_InvalidUserEmail)
+            .When(req => req.Email.HasValue());
+        RuleFor(req => req)
+            .Null()
+            .WithMessage(Resources.InviteOrganizationMemberRequestValidator_MissingUserIdAndEmail)
+            .When(req => req.UserId.HasNoValue() && req.Email.HasNoValue());
+        RuleFor(req => req)
+            .Null()
+            .WithMessage(Resources.InviteOrganizationMemberRequestValidator_BothUserIdAndEmail)
+            .When(req => req.UserId.HasValue() && req.Email.HasValue());
+    }
+}
\ No newline at end of file
diff --git a/src/OrganizationsInfrastructure/Api/Organizations/OrganizationsApi.cs b/src/OrganizationsInfrastructure/Api/Organizations/OrganizationsApi.cs
index 7cb00924..da31cabe 100644
--- a/src/OrganizationsInfrastructure/Api/Organizations/OrganizationsApi.cs
+++ b/src/OrganizationsInfrastructure/Api/Organizations/OrganizationsApi.cs
@@ -33,14 +33,14 @@ public async Task<ApiGetResult<Organization, GetOrganizationResponse>> Get(GetOr
         CancellationToken cancellationToken)
     {
         var organization =
-            await _organizationsApplication.GetOrganizationAsync(_contextFactory.Create(), request.Id,
+            await _organizationsApplication.GetOrganizationAsync(_contextFactory.Create(), request.Id!,
                 cancellationToken);
 
         return () =>
             organization.HandleApplicationResult<GetOrganizationResponse, Organization>(org =>
                 new GetOrganizationResponse { Organization = org });
     }
-    
+
 #if TESTINGONLY
     public async Task<ApiGetResult<OrganizationWithSettings, GetOrganizationSettingsResponse>> GetSettings(
         GetOrganizationSettingsRequest request, CancellationToken cancellationToken)
@@ -58,4 +58,31 @@ await _organizationsApplication.GetOrganizationSettingsAsync(_contextFactory.Cre
                 });
     }
 #endif
+
+    public async Task<ApiPostResult<Organization, InviteMemberToOrganizationResponse>> InviteMember(
+        InviteMemberToOrganizationRequest request,
+        CancellationToken cancellationToken)
+    {
+        var organization =
+            await _organizationsApplication.InviteMemberToOrganizationAsync(_contextFactory.Create(), request.Id!,
+                request.UserId, request.Email,
+                cancellationToken);
+
+        return () => organization.HandleApplicationResult<InviteMemberToOrganizationResponse, Organization>(org =>
+            new PostResult<InviteMemberToOrganizationResponse>(new InviteMemberToOrganizationResponse
+                { Organization = org }));
+    }
+
+    public async Task<ApiSearchResult<OrganizationMember, ListMembersForOrganizationResponse>> ListMembers(
+        ListMembersForOrganizationRequest request,
+        CancellationToken cancellationToken)
+    {
+        var members =
+            await _organizationsApplication.ListMembersForOrganizationAsync(_contextFactory.Create(), request.Id,
+                request.ToSearchOptions(), request.ToGetOptions(), cancellationToken);
+
+        return () =>
+            members.HandleApplicationResult(m =>
+                new ListMembersForOrganizationResponse { Members = m.Results, Metadata = m.Metadata });
+    }
 }
\ No newline at end of file
diff --git a/src/OrganizationsInfrastructure/Resources.Designer.cs b/src/OrganizationsInfrastructure/Resources.Designer.cs
index e5a93d97..4068e4a4 100644
--- a/src/OrganizationsInfrastructure/Resources.Designer.cs
+++ b/src/OrganizationsInfrastructure/Resources.Designer.cs
@@ -67,5 +67,32 @@ internal static string CreateOrganizationRequestValidator_InvalidName {
                 return ResourceManager.GetString("CreateOrganizationRequestValidator_InvalidName", resourceCulture);
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Only the &apos;Email&apos; or the &apos;UserId&apos; can be provided, not both.
+        /// </summary>
+        internal static string InviteOrganizationMemberRequestValidator_BothUserIdAndEmail {
+            get {
+                return ResourceManager.GetString("InviteOrganizationMemberRequestValidator_BothUserIdAndEmail", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to The &apos;Email&apos; is either missing or invalid.
+        /// </summary>
+        internal static string InviteOrganizationMemberRequestValidator_InvalidUserEmail {
+            get {
+                return ResourceManager.GetString("InviteOrganizationMemberRequestValidator_InvalidUserEmail", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Both the &apos;Email&apos; and &apos;UserId&apos; are missing.
+        /// </summary>
+        internal static string InviteOrganizationMemberRequestValidator_MissingUserIdAndEmail {
+            get {
+                return ResourceManager.GetString("InviteOrganizationMemberRequestValidator_MissingUserIdAndEmail", resourceCulture);
+            }
+        }
     }
 }
diff --git a/src/OrganizationsInfrastructure/Resources.resx b/src/OrganizationsInfrastructure/Resources.resx
index 038730c4..79c7f5e3 100644
--- a/src/OrganizationsInfrastructure/Resources.resx
+++ b/src/OrganizationsInfrastructure/Resources.resx
@@ -27,4 +27,13 @@
     <data name="CreateOrganizationRequestValidator_InvalidName" xml:space="preserve">
         <value>The 'Name' is either missing or invalid</value>
     </data>
+    <data name="InviteOrganizationMemberRequestValidator_InvalidUserEmail" xml:space="preserve">
+        <value>The 'Email' is either missing or invalid</value>
+    </data>
+    <data name="InviteOrganizationMemberRequestValidator_MissingUserIdAndEmail" xml:space="preserve">
+        <value>Both the 'Email' and 'UserId' are missing</value>
+    </data>
+    <data name="InviteOrganizationMemberRequestValidator_BothUserIdAndEmail" xml:space="preserve">
+        <value>Only the 'Email' or the 'UserId' can be provided, not both</value>
+    </data>
 </root>
\ No newline at end of file
diff --git a/src/UserProfilesApplication.UnitTests/UserProfileApplicationSpec.cs b/src/UserProfilesApplication.UnitTests/UserProfileApplicationSpec.cs
index f854e5f5..ce994d2d 100644
--- a/src/UserProfilesApplication.UnitTests/UserProfileApplicationSpec.cs
+++ b/src/UserProfilesApplication.UnitTests/UserProfileApplicationSpec.cs
@@ -51,7 +51,8 @@ public async Task WhenCreateProfileForAnyAndExistsForUserId_ThenReturnsError()
         _repository.Setup(rep => rep.FindByUserIdAsync(It.IsAny<Identifier>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(user.ToOptional());
 
-        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileType.Person, "apersonid",
+        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileClassification.Person,
+            "apersonid",
             "anemailaddress", "afirstname", "alastname", Timezones.Default.ToString(), CountryCodes.Default.ToString(),
             CancellationToken.None);
 
@@ -66,7 +67,8 @@ public async Task WhenCreateProfileForAnyAndExistsForEmailAddress_ThenReturnsErr
         _repository.Setup(rep => rep.FindByEmailAddressAsync(It.IsAny<EmailAddress>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(user.ToOptional());
 
-        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileType.Person, "apersonid",
+        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileClassification.Person,
+            "apersonid",
             "auser@company.com", "afirstname", "alastname", Timezones.Default.ToString(),
             CountryCodes.Default.ToString(),
             CancellationToken.None);
@@ -77,12 +79,13 @@ public async Task WhenCreateProfileForAnyAndExistsForEmailAddress_ThenReturnsErr
     [Fact]
     public async Task WhenCreateProfileAsyncForMachine_ThenCreatesProfile()
     {
-        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileType.Machine, "amachineid",
+        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileClassification.Machine,
+            "amachineid",
             "anemailaddress", "afirstname", "alastname", Timezones.Default.ToString(), CountryCodes.Default.ToString(),
             CancellationToken.None);
 
         result.Value.UserId.Should().Be("amachineid".ToId());
-        result.Value.Type.Should().Be(UserProfileType.Machine);
+        result.Value.Classification.Should().Be(UserProfileClassification.Machine);
         result.Value.DisplayName.Should().Be("afirstname");
         result.Value.Name.FirstName.Should().Be("afirstname");
         result.Value.Name.LastName.Should().BeNull();
@@ -108,12 +111,13 @@ public async Task WhenCreateProfileAsyncForMachine_ThenCreatesProfile()
     [Fact]
     public async Task WhenCreateProfileAsyncForPerson_ThenCreatesProfile()
     {
-        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileType.Person, "apersonid",
+        var result = await _application.CreateProfileAsync(_caller.Object, UserProfileClassification.Person,
+            "apersonid",
             "auser@company.com", "afirstname", "alastname", Timezones.Default.ToString(),
             CountryCodes.Default.ToString(), CancellationToken.None);
 
         result.Value.UserId.Should().Be("apersonid".ToId());
-        result.Value.Type.Should().Be(UserProfileType.Person);
+        result.Value.Classification.Should().Be(UserProfileClassification.Person);
         result.Value.DisplayName.Should().Be("afirstname");
         result.Value.Name.FirstName.Should().Be("afirstname");
         result.Value.Name.LastName.Should().Be("alastname");
@@ -309,4 +313,32 @@ public async Task WhenGetProfileAsync_ThenReturnsProfile()
         result.Value.Timezone.Should().Be(Timezones.Default.ToString());
         result.Value.Address.CountryCode.Should().Be(CountryCodes.Default.ToString());
     }
+
+    [Fact]
+    public async Task WhenGetAllProfilesAsyncAndNoIds_ThenReturnsProfiles()
+    {
+        var result = await _application.GetAllProfilesAsync(_caller.Object, new List<string>(), new GetOptions(),
+            CancellationToken.None);
+
+        result.Value.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task WhenGetAllProfilesAsync_ThenReturnsProfiles()
+    {
+        var profile = UserProfileRoot.Create(_recorder.Object, _idFactory.Object, ProfileType.Person, "auserid".ToId(),
+            PersonName.Create("afirstname", "alastname").Value).Value;
+        _repository.Setup(rep =>
+                rep.SearchAllByUserIdsAsync(It.IsAny<List<Identifier>>(), It.IsAny<CancellationToken>()))
+            .ReturnsAsync(new List<UserProfileRoot>
+            {
+                profile
+            });
+
+        var result = await _application.GetAllProfilesAsync(_caller.Object, new List<string> { "auserid" },
+            new GetOptions(), CancellationToken.None);
+
+        result.Value.Count.Should().Be(1);
+        result.Value[0].Id.Should().Be("anid");
+    }
 }
\ No newline at end of file
diff --git a/src/UserProfilesApplication/IUserProfilesApplication.cs b/src/UserProfilesApplication/IUserProfilesApplication.cs
index c9b9372b..535a0eea 100644
--- a/src/UserProfilesApplication/IUserProfilesApplication.cs
+++ b/src/UserProfilesApplication/IUserProfilesApplication.cs
@@ -15,13 +15,17 @@ Task<Result<UserProfile, Error>> ChangeProfileAsync(ICallerContext caller, strin
         string? lastName,
         string? displayName, string? phoneNumber, string? timezone, CancellationToken cancellationToken);
 
-    Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext caller, UserProfileType type, string userId,
+    Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext caller, UserProfileClassification classification,
+        string userId,
         string? emailAddress, string firstName, string? lastName, string? timezone, string? countryCode,
         CancellationToken cancellationToken);
 
     Task<Result<Optional<UserProfile>, Error>> FindPersonByEmailAddressAsync(ICallerContext caller, string emailAddress,
         CancellationToken cancellationToken);
 
+    Task<Result<List<UserProfile>, Error>> GetAllProfilesAsync(ICallerContext caller, List<string> ids,
+        GetOptions options, CancellationToken cancellationToken);
+
     Task<Result<UserProfile, Error>> GetProfileAsync(ICallerContext caller, string userId,
         CancellationToken cancellationToken);
 }
\ No newline at end of file
diff --git a/src/UserProfilesApplication/Persistence/IUserProfileRepository.cs b/src/UserProfilesApplication/Persistence/IUserProfileRepository.cs
index 66fa9a6c..142e35cd 100644
--- a/src/UserProfilesApplication/Persistence/IUserProfileRepository.cs
+++ b/src/UserProfilesApplication/Persistence/IUserProfileRepository.cs
@@ -17,4 +17,7 @@ Task<Result<Optional<UserProfileRoot>, Error>> FindByUserIdAsync(Identifier user
     Task<Result<UserProfileRoot, Error>> LoadAsync(Identifier id, CancellationToken cancellationToken);
 
     Task<Result<UserProfileRoot, Error>> SaveAsync(UserProfileRoot profile, CancellationToken cancellationToken);
+
+    Task<Result<List<UserProfileRoot>, Error>> SearchAllByUserIdsAsync(List<Identifier> ids,
+        CancellationToken cancellationToken);
 }
\ No newline at end of file
diff --git a/src/UserProfilesApplication/UserProfilesApplication.cs b/src/UserProfilesApplication/UserProfilesApplication.cs
index cfde1a97..4bd1dd5c 100644
--- a/src/UserProfilesApplication/UserProfilesApplication.cs
+++ b/src/UserProfilesApplication/UserProfilesApplication.cs
@@ -26,11 +26,12 @@ public UserProfilesApplication(IRecorder recorder, IIdentifierFactory identifier
         _repository = repository;
     }
 
-    public async Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext caller, UserProfileType type,
+    public async Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext caller,
+        UserProfileClassification classification,
         string userId, string? emailAddress, string firstName, string? lastName, string? timezone, string? countryCode,
         CancellationToken cancellationToken)
     {
-        if (type == UserProfileType.Person && emailAddress.HasNoValue())
+        if (classification == UserProfileClassification.Person && emailAddress.HasNoValue())
         {
             return Error.RuleViolation(Resources.UserProfilesApplication_PersonMustHaveEmailAddress);
         }
@@ -46,7 +47,7 @@ public async Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext
             return Error.EntityExists(Resources.UserProfilesApplication_ProfileExistsForUser);
         }
 
-        if (type == UserProfileType.Person && emailAddress.HasValue())
+        if (classification == UserProfileClassification.Person && emailAddress.HasValue())
         {
             var email = EmailAddress.Create(emailAddress);
             if (!email.IsSuccessful)
@@ -66,7 +67,7 @@ public async Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext
             }
         }
 
-        var name = PersonName.Create(firstName, type == UserProfileType.Person
+        var name = PersonName.Create(firstName, classification == UserProfileClassification.Person
             ? lastName
             : Optional<string>.None);
         if (!name.IsSuccessful)
@@ -74,7 +75,8 @@ public async Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext
             return name.Error;
         }
 
-        var created = UserProfileRoot.Create(_recorder, _identifierFactory, type.ToEnumOrDefault(ProfileType.Person),
+        var created = UserProfileRoot.Create(_recorder, _identifierFactory,
+            classification.ToEnumOrDefault(ProfileType.Person),
             userId.ToId(), name.Value);
         if (!created.IsSuccessful)
         {
@@ -82,7 +84,7 @@ public async Task<Result<UserProfile, Error>> CreateProfileAsync(ICallerContext
         }
 
         var profile = created.Value;
-        if (type == UserProfileType.Person)
+        if (classification == UserProfileClassification.Person)
         {
             var email2 = EmailAddress.Create(emailAddress!);
             if (!email2.IsSuccessful)
@@ -328,6 +330,35 @@ public async Task<Result<UserProfile, Error>> ChangeContactAddressAsync(ICallerC
 
         return saved.Value.ToProfile();
     }
+
+    public async Task<Result<List<UserProfile>, Error>> GetAllProfilesAsync(ICallerContext caller, List<string> ids,
+        GetOptions options, CancellationToken cancellationToken)
+    {
+        if (ids.HasNone())
+        {
+            return new List<UserProfile>();
+        }
+
+        var retrieved =
+            await _repository.SearchAllByUserIdsAsync(ids.Select(id => id.ToId()).ToList(), cancellationToken);
+        if (!retrieved.IsSuccessful)
+        {
+            return retrieved.Error;
+        }
+
+        var profiles = retrieved.Value;
+        if (profiles.HasNone())
+        {
+            return new List<UserProfile>();
+        }
+
+        _recorder.TraceInformation(caller.ToCall(),
+            "Profiles were retrieved for {ExpectedCount} users, and returned {ActualCount} profiles", ids.Count,
+            profiles.Count);
+        return profiles
+            .ConvertAll(profile => profile.ToProfile())
+            .ToList();
+    }
 }
 
 internal static class UserProfileConversionExtensions
@@ -337,7 +368,7 @@ public static UserProfile ToProfile(this UserProfileRoot profile)
         return new UserProfile
         {
             Id = profile.Id,
-            Type = profile.Type.ToEnumOrDefault(UserProfileType.Person),
+            Classification = profile.Type.ToEnumOrDefault(UserProfileClassification.Person),
             UserId = profile.UserId,
             Name = profile.Name.ToName(),
             DisplayName = profile.DisplayName.ValueOrDefault!,
diff --git a/src/UserProfilesInfrastructure/ApplicationServices/UserProfilesInProcessServiceClient.cs b/src/UserProfilesInfrastructure/ApplicationServices/UserProfilesInProcessServiceClient.cs
index b2dc9d66..2c433894 100644
--- a/src/UserProfilesInfrastructure/ApplicationServices/UserProfilesInProcessServiceClient.cs
+++ b/src/UserProfilesInfrastructure/ApplicationServices/UserProfilesInProcessServiceClient.cs
@@ -19,7 +19,8 @@ public async Task<Result<UserProfile, Error>> CreateMachineProfilePrivateAsync(I
         string machineId, string name, string? timezone,
         string? countryCode, CancellationToken cancellationToken)
     {
-        return await _userProfilesApplication.CreateProfileAsync(caller, UserProfileType.Machine, machineId, null, name,
+        return await _userProfilesApplication.CreateProfileAsync(caller, UserProfileClassification.Machine, machineId,
+            null, name,
             null, timezone, countryCode, cancellationToken);
     }
 
@@ -27,7 +28,8 @@ public async Task<Result<UserProfile, Error>> CreatePersonProfilePrivateAsync(IC
         string personId, string emailAddress, string firstName,
         string? lastName, string? timezone, string? countryCode, CancellationToken cancellationToken)
     {
-        return await _userProfilesApplication.CreateProfileAsync(caller, UserProfileType.Person, personId, emailAddress,
+        return await _userProfilesApplication.CreateProfileAsync(caller, UserProfileClassification.Person, personId,
+            emailAddress,
             firstName, lastName, timezone, countryCode, cancellationToken);
     }
 
@@ -37,6 +39,12 @@ public async Task<Result<Optional<UserProfile>, Error>> FindPersonByEmailAddress
         return await _userProfilesApplication.FindPersonByEmailAddressAsync(caller, emailAddress, cancellationToken);
     }
 
+    public async Task<Result<List<UserProfile>, Error>> GetAllProfilesPrivateAsync(ICallerContext caller,
+        List<string> ids, GetOptions options, CancellationToken cancellationToken)
+    {
+        return await _userProfilesApplication.GetAllProfilesAsync(caller, ids, options, cancellationToken);
+    }
+
     public async Task<Result<UserProfile, Error>> GetProfilePrivateAsync(ICallerContext caller, string userId,
         CancellationToken cancellationToken)
     {
diff --git a/src/UserProfilesInfrastructure/Persistence/UserProfileRepository.cs b/src/UserProfilesInfrastructure/Persistence/UserProfileRepository.cs
index 7bd889eb..c356cc5d 100644
--- a/src/UserProfilesInfrastructure/Persistence/UserProfileRepository.cs
+++ b/src/UserProfilesInfrastructure/Persistence/UserProfileRepository.cs
@@ -55,6 +55,16 @@ public async Task<Result<UserProfileRoot, Error>> SaveAsync(UserProfileRoot prof
         return profile;
     }
 
+    public async Task<Result<List<UserProfileRoot>, Error>> SearchAllByUserIdsAsync(List<Identifier> ids,
+        CancellationToken cancellationToken)
+    {
+        var tasks = await Task.WhenAll(ids.Select(async id => await FindByUserIdAsync(id, cancellationToken)));
+        return tasks.ToList()
+            .Where(task => task is { IsSuccessful: true, HasValue: true })
+            .Select(task => task.Value.Value)
+            .ToList();
+    }
+
     public async Task<Result<Optional<UserProfileRoot>, Error>> FindByUserIdAsync(Identifier userId,
         CancellationToken cancellationToken)
     {