diff --git a/counterexamples/bad-entityId.json b/counterexamples/bad-entityId.json
new file mode 100644
index 00000000..501e0e72
--- /dev/null
+++ b/counterexamples/bad-entityId.json
@@ -0,0 +1,11 @@
+{
+  "id": "featureWithBadEntityId",
+  "type": "Feature",
+  "geometry": {
+    "type": "Point",
+    "coordinates": [0, 1]
+  },
+  "properties": {
+    "entityId": "1423"
+  }
+}
diff --git a/examples/admins/locality/admin-named-locality.yaml b/examples/admins/locality/admin-named-locality.yaml
index 40018fec..64fcf6f3 100644
--- a/examples/admins/locality/admin-named-locality.yaml
+++ b/examples/admins/locality/admin-named-locality.yaml
@@ -1,9 +1,11 @@
+id: capitolHillFeatureId
 geometry:
   coordinates:
   - -122.3183680
   - 47.6238307
   type: Point
 properties:
+  entityId: 08628d542fffffff0100000000052a6f
   context: seattleId
   localityType: neighborhood
   names:
diff --git a/schema/defs.yaml b/schema/defs.yaml
index 0def7fff..4a23898e 100644
--- a/schema/defs.yaml
+++ b/schema/defs.yaml
@@ -4,6 +4,11 @@ title: Overture Maps Feature Schema Common Definitions
 description: Common schema definitions shared by all themes
 "$defs":
   propertyDefinitions:
+    entityId:
+      description: >-
+        Optional stable identifier for the feature. 128 bits represented as 32 hex characters.
+      type: string
+      pattern: ^[0-9a-f]{32}$
     level:
       description: Z-order of the feature where 0 is visual level
       type: integer
@@ -241,6 +246,7 @@ description: Common schema definitions shared by all themes
         ^ext.*$:
           description: "Additional top-level properties must be prefixed with `ext`."
       properties:
+        entityId: { "$ref": "#/$defs/propertyDefinitions/entityId" }
         theme: { "$ref": "#/$defs/propertyDefinitions/theme" }
         type: { "$ref": "#/$defs/propertyDefinitions/featureType" }
         version: { "$ref": "#/$defs/propertyDefinitions/featureVersion" }