diff --git a/CedarJava/src/main/java/com/cedarpolicy/model/entity/Entity.java b/CedarJava/src/main/java/com/cedarpolicy/model/entity/Entity.java
index ecef28c..00366e8 100644
--- a/CedarJava/src/main/java/com/cedarpolicy/model/entity/Entity.java
+++ b/CedarJava/src/main/java/com/cedarpolicy/model/entity/Entity.java
@@ -25,8 +25,8 @@
 /**
  * An entity is the kind of object about which authorization decisions are made; principals,
  * actions, and resources are all a kind of entity. Each entity is defined by its entity type, a
- * unique identifier (UID), zero or more attributes mapped to values, and zero or more parent
- * entities.
+ * unique identifier (UID), zero or more attributes mapped to values, zero or more parent
+ * entities, and zero or more tags.
  */
 public class Entity {
     private final EntityUID euid;
@@ -37,6 +37,9 @@ public class Entity {
     /** Set of entity EUIDs that are parents to this entity. */
     public final Set<EntityUID> parentsEUIDs;
 
+    /** Tags on this entity (RFC 82) */
+    public final Map<String, Value> tags;
+
     /**
      * Create an entity from an EntityUIDs, a map of attributes, and a set of parent EntityUIDs.
      *
@@ -45,9 +48,22 @@ public class Entity {
      * @param parentsEUIDs Set of parent entities' EUIDs.
      */
     public Entity(EntityUID uid, Map<String, Value> attributes, Set<EntityUID> parentsEUIDs) {
+        this(uid, attributes, parentsEUIDs, new HashMap<>());
+    }
+
+    /**
+     * Create an entity from an EntityUIDs, a map of attributes, a set of parent EntityUIDs, and a map of tags.
+     *
+     * @param uid EUID of the Entity.
+     * @param attributes Key/Value map of attributes.
+     * @param parentsEUIDs Set of parent entities' EUIDs.
+     * @param tags Key/Value map of tags.
+     */
+    public Entity(EntityUID uid, Map<String, Value> attributes, Set<EntityUID> parentsEUIDs, Map<String, Value> tags) {
         this.attrs = new HashMap<>(attributes);
         this.euid = uid;
         this.parentsEUIDs = parentsEUIDs;
+        this.tags = new HashMap<>(tags);
     }
 
     @Override
@@ -66,7 +82,15 @@ public String toString() {
                                     .map(e -> e.getKey() + ": " + e.getValue())
                                     .collect(Collectors.joining("\n\t\t"));
         }
-        return euid.toString() + parentStr + attributeStr;
+        String tagsStr = "";
+        if (!tags.isEmpty()) {
+            tagsStr =
+                    "\n\ttags:\n\t\t"
+                            + tags.entrySet().stream()
+                                    .map(e -> e.getKey() + ": " + e.getValue())
+                                    .collect(Collectors.joining("\n\t\t"));
+        }
+        return euid.toString() + parentStr + attributeStr + tagsStr;
     }
 
 
@@ -79,10 +103,18 @@ public EntityUID getEUID() {
     }
 
     /**
-     * Get this Entities parents
+     * Get this Entity's parents
      * @return the set of parent EntityUIDs
      */
     public Set<EntityUID> getParents() {
         return parentsEUIDs;
     }
+
+    /**
+     * Get this Entity's tags
+     * @return the map of tags
+     */
+    public Map<String, Value> getTags() {
+        return tags;
+    }
 }
diff --git a/CedarJava/src/main/java/com/cedarpolicy/serializer/EntitySerializer.java b/CedarJava/src/main/java/com/cedarpolicy/serializer/EntitySerializer.java
index fccf4e5..c7cd142 100644
--- a/CedarJava/src/main/java/com/cedarpolicy/serializer/EntitySerializer.java
+++ b/CedarJava/src/main/java/com/cedarpolicy/serializer/EntitySerializer.java
@@ -37,6 +37,7 @@ public void serialize(
         jsonGenerator.writeObjectField("attrs", entity.attrs);
         jsonGenerator.writeObjectField("parents",
                 entity.getParents().stream().map(EntityUID::asJson).collect(Collectors.toSet()));
+        jsonGenerator.writeObjectField("tags", entity.tags);
         jsonGenerator.writeEndObject();
     }
 }
diff --git a/CedarJava/src/test/java/com/cedarpolicy/EntityValidationTests.java b/CedarJava/src/test/java/com/cedarpolicy/EntityValidationTests.java
index 812e1a6..6cfc2b3 100644
--- a/CedarJava/src/test/java/com/cedarpolicy/EntityValidationTests.java
+++ b/CedarJava/src/test/java/com/cedarpolicy/EntityValidationTests.java
@@ -35,7 +35,7 @@
 import com.cedarpolicy.pbt.EntityGen;
 import com.cedarpolicy.value.EntityTypeName;
 import com.cedarpolicy.value.PrimBool;
-
+import com.cedarpolicy.value.PrimString;
 
 /**
  * Tests for entity validator
@@ -96,6 +96,24 @@ public void testEntitiesWithCyclicParentRelationship() throws AuthException {
                 "Expected to match regex but was: '%s'".formatted(errMsg));
     }
 
+    /**
+     * Test that an entity with a tag not specified in the schema throws an exception.
+     */
+    @Test
+    public void testEntityWithUnknownTag() throws AuthException {
+        Entity entity = EntityValidationTests.entityGen.arbitraryEntity();
+        entity.tags.put("test", new PrimString("value"));
+
+        EntityValidationRequest request = new EntityValidationRequest(ROLE_SCHEMA, List.of(entity));
+
+        BadRequestException exception = assertThrows(BadRequestException.class, () -> engine.validateEntities(request));
+
+        String errMsg = exception.getErrors().get(0);
+        assertTrue(errMsg.matches("found a tag `test` on `Role::\".*\"`, "
+            + "but no tags should exist on `Role::\".*\"` according to the schema"),
+            "Expected to match regex but was: '%s'".formatted(errMsg));
+    }
+
     @BeforeAll
     public static void setUp() {
 
diff --git a/CedarJava/src/test/java/com/cedarpolicy/SharedIntegrationTests.java b/CedarJava/src/test/java/com/cedarpolicy/SharedIntegrationTests.java
index 631dbff..68cb7cf 100644
--- a/CedarJava/src/test/java/com/cedarpolicy/SharedIntegrationTests.java
+++ b/CedarJava/src/test/java/com/cedarpolicy/SharedIntegrationTests.java
@@ -26,6 +26,8 @@
 import com.cedarpolicy.model.AuthorizationResponse;
 import com.cedarpolicy.model.ValidationRequest;
 import com.cedarpolicy.model.ValidationResponse;
+import com.cedarpolicy.model.ValidationResponse.ValidationError;
+import com.cedarpolicy.model.ValidationResponse.ValidationSuccessResponse;
 import com.cedarpolicy.model.AuthorizationSuccessResponse.Decision;
 import com.cedarpolicy.model.exception.AuthException;
 import com.cedarpolicy.model.exception.BadRequestException;
@@ -51,6 +53,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -173,6 +176,12 @@ private static class JsonEntity {
                 value = "UWF_UNWRITTEN_PUBLIC_OR_PROTECTED_FIELD",
                 justification = "Initialized by Jackson.")
         public List<JsonEUID> parents;
+
+        /** Entity tags, where the value string is a Cedar literal value. */
+        @SuppressFBWarnings(
+            value = "UWF_UNWRITTEN_PUBLIC_OR_PROTECTED_FIELD",
+            justification = "Initialized by Jackson.")
+        public Map<String, Value> tags;
     }
 
     /**
@@ -296,8 +305,10 @@ private Entity loadEntity(JsonEntity je) {
             .map(euid -> EntityUID.parseFromJson(euid).get())
             .collect(Collectors.toSet());
 
+        // Support tags while also supporting old JsonEntity objects that don't specify tags
+        Map<String, Value> tags = je.tags != null ? je.tags : new HashMap<>();
 
-        return new Entity(EntityUID.parseFromJson(je.uid).get(), je.attrs, parents);
+        return new Entity(EntityUID.parseFromJson(je.uid).get(), je.attrs, parents, tags);
     }
 
     /**
@@ -326,7 +337,13 @@ private void executeJsonValidationTest(PolicySet policies, Schema schema, Boolea
             ValidationResponse result = auth.validate(validationQuery);
             assertEquals(result.type, ValidationResponse.SuccessOrFailure.Success);
             if (shouldValidate) {
-                assertTrue(result.validationPassed());
+                ValidationSuccessResponse validationSuccessResponse = result.success.get();
+
+                // Assemble the validation failure messages, if any
+                List<ValidationError> valErrList = List.copyOf(validationSuccessResponse.validationErrors);
+                String validationErrorMessages = valErrList.stream().map(e -> e.getError().message).collect(Collectors.joining(", "));
+
+                assertTrue(result.validationPassed(), validationErrorMessages);
             }
         } catch (BadRequestException e) {
             // A `BadRequestException` is the results of a parsing error.