diff --git a/schema/1.0.0/event.schema.json b/schema/1.0.0/event.schema.json
index 9c9b290..68ccebe 100644
--- a/schema/1.0.0/event.schema.json
+++ b/schema/1.0.0/event.schema.json
@@ -52,11 +52,17 @@
       "examples": ["84266fdbd31d4c2c6d0665f7e8380fa3"]
     },
     "client_id": {
-      "description": "The client issuing the query.  This could be a unique browser, a microservice that performs searches, a crawling bot. If only authenticated users are tracked, then you could use a specific user id here, otherwise you should use something permanent and track user id as an _Additional Property_.",
+      "description": "The client issuing the query.  This could be a unique browser, a microservice that performs searches, a crawling bot.",
       "type": "string",
       "maxLength": 100,
       "examples": ["5e3b2a1c-8b7d-4f2e-a3d4-c9b2e1f3a4b5","quepid-nightly-bot", "BugsBunny::Firefox@0967084"]
     },    
+    "user_id": {
+      "description": "The user ID associated with the person performing the interactions being logged on the site. Can be null/empty in case of an unauthenticated user.",
+      "type": "string",
+      "maxLength": 100,
+      "examples": ["5e3b2a1c-8b7d-4f2e-a3d4-c9b2e1f3a4b5"]
+    },
     "timestamp": {
       "description": "When the event took place.",
       "type": "string",