diff --git a/modules/core/shared/src/main/scala/lucuma/core/enums/PartnerLinkType.scala b/modules/core/shared/src/main/scala/lucuma/core/enums/PartnerLinkType.scala
new file mode 100644
index 00000000..a267e958
--- /dev/null
+++ b/modules/core/shared/src/main/scala/lucuma/core/enums/PartnerLinkType.scala
@@ -0,0 +1,14 @@
+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.enums
+
+import lucuma.core.util.Enumerated
+
+enum PartnerLinkType(val tag: String) derives Enumerated:
+
+  case HasPartner            extends PartnerLinkType("has_partner")
+  case HasNonPartner         extends PartnerLinkType("has_non_partner")
+  case HasUnspecifiedPartner extends PartnerLinkType("has_unspecified_partner")
+
+end PartnerLinkType
diff --git a/modules/core/shared/src/main/scala/lucuma/core/enums/ProgramUserRole.scala b/modules/core/shared/src/main/scala/lucuma/core/enums/ProgramUserRole.scala
new file mode 100644
index 00000000..55315865
--- /dev/null
+++ b/modules/core/shared/src/main/scala/lucuma/core/enums/ProgramUserRole.scala
@@ -0,0 +1,15 @@
+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.enums
+
+import lucuma.core.util.Enumerated
+
+enum ProgramUserRole(val tag: String) derives Enumerated:
+
+  case Pi      extends ProgramUserRole("pi")
+  case Coi     extends ProgramUserRole("coi")
+  case CoiRO   extends ProgramUserRole("coi_ro")
+  case Support extends ProgramUserRole("support")
+
+end ProgramUserRole
\ No newline at end of file
diff --git a/modules/core/shared/src/main/scala/lucuma/core/model/PartnerLink.scala b/modules/core/shared/src/main/scala/lucuma/core/model/PartnerLink.scala
new file mode 100644
index 00000000..1ea667bd
--- /dev/null
+++ b/modules/core/shared/src/main/scala/lucuma/core/model/PartnerLink.scala
@@ -0,0 +1,102 @@
+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.model
+
+
+
+import cats.Eq
+import cats.syntax.either.*
+import lucuma.core.enums.Partner
+import lucuma.core.enums.PartnerLinkType
+import monocle.Iso
+
+
+/**
+ * Embodies the association between a user and a partner, if any.  There are
+ * three possible values: `HasPartner` (meaning the user is tied to a particular
+ * `Partner`), `HasNonPartner` (the user is explicitly not associated with any
+ * `Partner`) and `HasUnspecifiedPartner` (the relationship is not yet
+ * determined).
+ */
+sealed trait PartnerLink extends Product with Serializable:
+
+  def linkType: PartnerLinkType =
+    fold(
+      PartnerLinkType.HasUnspecifiedPartner,
+      PartnerLinkType.HasNonPartner,
+      _ => PartnerLinkType.HasPartner
+    )
+
+  /**
+   * Converts to an either where Left(true) is `HasNonPartner`, Left(false) is
+   * `HasUnspecifiedPartner` and Right(partner) is `HasPartner`.
+   */
+  def toEither: Either[Boolean, Partner] =
+    fold(false.asLeft, true.asLeft, _.asRight)
+
+  /**
+   * Creates an Option[Partner] which is Some when this link is `HasPartner`.
+   */
+  def partnerOption: Option[Partner] =
+    toEither.toOption
+
+  /**
+   * True only if HasNonPartner.
+   */
+  def isNonPartner: Boolean =
+    fold(false, true, _ => false)
+
+  /**
+   * True if HasPartner or HasNonPartner.
+   */
+  def isSet: Boolean =
+    fold(false, true, _ => true)
+
+  /**
+   * True only if HasUnspecifiedPartner.  Same as `!isSet`.
+   */
+  def isUnspecified: Boolean =
+    !isSet
+
+  def fold[A](unspecified: => A, hasNonPartner: => A, hasPartner: Partner => A): A =
+    this match {
+      case PartnerLink.HasUnspecifiedPartner => unspecified
+      case PartnerLink.HasNonPartner         => hasNonPartner
+      case PartnerLink.HasPartner(p)         => hasPartner(p)
+    }
+end PartnerLink
+
+object PartnerLink:
+
+  case class HasPartner(partner: Partner) extends PartnerLink
+  case object HasNonPartner               extends PartnerLink
+  case object HasUnspecifiedPartner       extends PartnerLink
+
+  given Eq[PartnerLink] =
+    Eq.by(_.toEither)
+
+  private def fromEither(e: Either[Boolean, Partner]): PartnerLink =
+    e.fold(b => if (b) HasNonPartner else HasUnspecifiedPartner, HasPartner.apply)
+
+  /**
+   * Iso for an Either where Left(true) is HasNoPartner and Left(false) is
+   * HasUnspecifiedPartner.
+   */
+  val either: Iso[PartnerLink, Either[Boolean, Partner]] =
+    Iso[PartnerLink, Either[Boolean, Partner]](_.toEither)(fromEither)
+
+  /**
+   * Creates a `PartnerLink` where a None value for `Partner` is interpreted as
+   * `HasNonPartner`.
+   */
+  def asNonPartner(p: Option[Partner]): PartnerLink =
+    p.fold(HasNonPartner)(HasPartner.apply)
+
+  def fromLinkType(linkType: PartnerLinkType, partner: Option[Partner] = None): Either[String, PartnerLink] =
+    linkType match
+      case PartnerLinkType.HasPartner            => partner.map(HasPartner.apply).toRight("HasPartner instance missing partner")
+      case PartnerLinkType.HasNonPartner         => HasNonPartner.asRight
+      case PartnerLinkType.HasUnspecifiedPartner => HasUnspecifiedPartner.asRight
+
+end PartnerLink
\ No newline at end of file
diff --git a/modules/testkit/src/main/scala/lucuma/core/model/arb/ArbPartnerLink.scala b/modules/testkit/src/main/scala/lucuma/core/model/arb/ArbPartnerLink.scala
new file mode 100644
index 00000000..8a802265
--- /dev/null
+++ b/modules/testkit/src/main/scala/lucuma/core/model/arb/ArbPartnerLink.scala
@@ -0,0 +1,44 @@
+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.model
+package arb
+
+import lucuma.core.enums.Partner
+import lucuma.core.enums.PartnerLinkType
+import lucuma.core.util.arb.ArbEnumerated
+import org.scalacheck.*
+import org.scalacheck.Arbitrary.arbitrary
+import org.scalacheck.Gen.const
+
+
+trait ArbPartnerLink {
+
+  import ArbEnumerated.given
+
+  given Arbitrary[PartnerLink.HasPartner] =
+    Arbitrary {
+      arbitrary[Partner].map(PartnerLink.HasPartner.apply)
+    }
+
+  given Cogen[PartnerLink.HasPartner] =
+    Cogen[Partner].contramap(_.partner)
+
+  given Arbitrary[PartnerLink] =
+    Arbitrary {
+      Gen.oneOf(
+        arbitrary[PartnerLink.HasPartner],
+        const(PartnerLink.HasNonPartner),
+        const(PartnerLink.HasUnspecifiedPartner)
+      )
+    }
+
+  given Cogen[PartnerLink] =
+    Cogen[(PartnerLinkType, Option[Partner])].contramap { a => (
+      a.linkType,
+      a.partnerOption
+    )}
+
+}
+
+object ArbPartnerLink extends ArbPartnerLink
\ No newline at end of file
diff --git a/modules/tests/shared/src/test/scala/lucuma/core/model/PartnerLinkSuite.scala b/modules/tests/shared/src/test/scala/lucuma/core/model/PartnerLinkSuite.scala
new file mode 100644
index 00000000..140aca9b
--- /dev/null
+++ b/modules/tests/shared/src/test/scala/lucuma/core/model/PartnerLinkSuite.scala
@@ -0,0 +1,16 @@
+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.model
+
+import cats.kernel.laws.discipline.EqTests
+import lucuma.core.model.arb.ArbPartnerLink
+import munit.*
+
+final class PartnerLinkSuite extends DisciplineSuite:
+
+  import ArbPartnerLink.given
+
+  checkAll("PartnerLink", EqTests[PartnerLink].eqv)
+
+end PartnerLinkSuite
\ No newline at end of file