diff --git a/ontology/uco/action/action.ttl b/ontology/uco/action/action.ttl
index d5a5bf26..95b4e3c5 100644
--- a/ontology/uco/action/action.ttl
+++ b/ontology/uco/action/action.ttl
@@ -40,6 +40,7 @@ action:Action
 	rdfs:subClassOf core:UcoObject ;
 	rdfs:label "Action"@en ;
 	rdfs:comment "An action is something that may be done or performed."@en ;
+	owl:disjointWith core:Event ;
 	sh:property
 		[
 			sh:class action:Action ;
@@ -150,6 +151,16 @@ action:Action
 	sh:targetClass action:Action ;
 	.
 
+action:Action-disjointWith-Event-shape
+	a sh:NodeShape ;
+	sh:message "action:Action and core:Event are disjoint classes."@en ;
+	sh:not [
+		a sh:NodeShape ;
+		sh:class core:Event ;
+	] ;
+	sh:targetClass action:Action ;
+	.
+
 action:ActionArgumentFacet
 	a
 		owl:Class ,
diff --git a/ontology/uco/core/core.ttl b/ontology/uco/core/core.ttl
index 7accb6fa..bdb092e4 100644
--- a/ontology/uco/core/core.ttl
+++ b/ontology/uco/core/core.ttl
@@ -1,3 +1,4 @@
+@prefix action: <https://ontology.unifiedcyberontology.org/uco/action/> .
 @prefix core: <https://ontology.unifiedcyberontology.org/uco/core/> .
 @prefix owl: <http://www.w3.org/2002/07/owl#> .
 @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@@ -15,6 +16,11 @@
 	owl:versionIRI core:1.2.0 ;
 	.
 
+action:Action
+	a owl:Class ;
+	rdfs:isDefinedBy <https://ontology.unifiedcyberontology.org/uco/types> ;
+	.
+
 core:Annotation
 	a
 		owl:Class ,
@@ -179,6 +185,7 @@ core:Event
 	rdfs:subClassOf core:UcoObject ;
 	rdfs:label "Event"@en ;
 	rdfs:comment "An Event is a noteworthy occurrence (something that happens or might happen)."@en ;
+	owl:disjointWith action:Action ;
 	sh:property
 		[
 			sh:class core:UcoObject ;
diff --git a/tests/examples/Makefile b/tests/examples/Makefile
index 56d619d1..80f59e04 100644
--- a/tests/examples/Makefile
+++ b/tests/examples/Makefile
@@ -27,6 +27,7 @@ all: \
   configuration_setting_XFAIL_validation.ttl \
   database_records_PASS_validation.ttl \
   database_records_XFAIL_validation.ttl \
+  event_XFAIL_validation.ttl \
   file_url_PASS_validation.ttl \
   has_facet_inverse_functional_PASS_validation.ttl \
   has_facet_inverse_functional_XFAIL_validation.ttl \
@@ -97,6 +98,7 @@ check: \
   configuration_setting_XFAIL_validation.ttl \
   database_records_PASS_validation.ttl \
   database_records_XFAIL_validation.ttl \
+  event_XFAIL_validation.ttl \
   file_url_PASS_validation.ttl \
   has_facet_inverse_functional_PASS_validation.ttl \
   has_facet_inverse_functional_XFAIL_validation.ttl \
diff --git a/tests/examples/event_XFAIL.json b/tests/examples/event_XFAIL.json
new file mode 100644
index 00000000..9f2a59d9
--- /dev/null
+++ b/tests/examples/event_XFAIL.json
@@ -0,0 +1,28 @@
+{
+    "@context": {
+        "kb": "http://example.org/kb/",
+        "action": "https://ontology.unifiedcyberontology.org/uco/action/",
+        "core": "https://ontology.unifiedcyberontology.org/uco/core/",
+        "xsd": "http://www.w3.org/2001/XMLSchema#"
+    },
+    "@graph": [
+        {
+            "@id": "kb:Action-0-03ee1fe6-12cf-4a35-b7dd-06d4e69369b5",
+            "@type": [
+                "action:Action",
+                "core:Event"
+            ],
+            "rdfs:comment": "This node will trigger an XFAIL for designating itself an Action and Event, which are disjoint classes."
+        },
+        {
+            "@id": "kb:Action-1-763c1ff2-d18d-427b-aa82-30d90701a644",
+            "@type": "action:Action",
+            "rdfs:comment": "This node should pass validation."
+        },
+        {
+            "@id": "kb:Event-1-ee9450b6-3535-473d-984d-17a91408a54f",
+            "@type": "event:Event",
+            "rdfs:comment": "This node should pass validation."
+        }
+    ]
+}
diff --git a/tests/examples/event_XFAIL_validation.ttl b/tests/examples/event_XFAIL_validation.ttl
new file mode 100644
index 00000000..be6dbd96
--- /dev/null
+++ b/tests/examples/event_XFAIL_validation.ttl
@@ -0,0 +1,21 @@
+@prefix action: <https://ontology.unifiedcyberontology.org/uco/action/> .
+@prefix owl: <http://www.w3.org/2002/07/owl#> .
+@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix sh: <http://www.w3.org/ns/shacl#> .
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
+
+[]
+	a sh:ValidationReport ;
+	sh:conforms "false"^^xsd:boolean ;
+	sh:result [
+		a sh:ValidationResult ;
+		sh:focusNode <http://example.org/kb/Action-0-03ee1fe6-12cf-4a35-b7dd-06d4e69369b5> ;
+		sh:resultMessage "action:Action and core:Event are disjoint classes."@en ;
+		sh:resultSeverity sh:Violation ;
+		sh:sourceConstraintComponent sh:NotConstraintComponent ;
+		sh:sourceShape action:Action-disjointWith-Event-shape ;
+		sh:value <http://example.org/kb/Action-0-03ee1fe6-12cf-4a35-b7dd-06d4e69369b5> ;
+	] ;
+	.
+
diff --git a/tests/examples/test_validation.py b/tests/examples/test_validation.py
index 285dfdec..c714d0c3 100644
--- a/tests/examples/test_validation.py
+++ b/tests/examples/test_validation.py
@@ -207,6 +207,15 @@ def test_database_records_XFAIL() -> None:
       }
     )
 
+def test_event_XFAIL() -> None:
+    confirm_validation_results(
+        "event_XFAIL_validation.ttl",
+        False,
+        expected_focus_node_severities = {
+          ("http://example.org/kb/Action-0-03ee1fe6-12cf-4a35-b7dd-06d4e69369b5", str(NS_SH.Violation)),
+        }
+    )
+
 def test_file_url_PASS_validation() -> None:
     confirm_validation_results(
       "file_url_PASS_validation.ttl",