diff --git a/docs/specification/reference.md b/docs/specification/reference.md
index 9d296028..5b604295 100644
--- a/docs/specification/reference.md
+++ b/docs/specification/reference.md
@@ -39,6 +39,16 @@ The top-level structure of a discovery document (`/.well-known/ucp`).
 
 {{ extension_schema_fields('ucp.json#/$defs/discovery_profile', 'reference') }}
 
+### Services
+Services define the API surface for a vertical (shopping, common, etc.) with
+transport bindings. Each service is keyed by its reverse-domain name
+(e.g., `dev.ucp.shopping`) in the discovery profile's `services` object.
+
+{{ extension_schema_fields('ucp.json#/$defs/services', 'reference') }}
+
+#### Service Schema
+{{ schema_fields('service_schema', 'reference') }}
+
 ### Checkout Response Metadata
 The `ucp` object included in checkout responses.
 
diff --git a/main.py b/main.py
index a4ca60f4..e8f0fa9f 100644
--- a/main.py
+++ b/main.py
@@ -49,6 +49,7 @@ def define_env(env):
     "spec/schemas/",
     "spec/schemas/shopping/",
     "spec/schemas/shopping/types/",
+    "spec/services/",
   ]
 
   def _load_json_file(entity_name):
diff --git a/source/schemas/ucp.json b/source/schemas/ucp.json
index b532a104..b0746bbb 100644
--- a/source/schemas/ucp.json
+++ b/source/schemas/ucp.json
@@ -14,6 +14,11 @@
     "services": {
       "type": "object",
       "description": "Service definitions keyed by reverse-domain service name.",
+      "properties": {
+        "com.example.service": {
+          "$ref": "../services/service_schema.json"
+        }
+      },
       "additionalProperties": {"$ref": "../services/service_schema.json"}
     },
 
diff --git a/spec/schemas/ucp.json b/spec/schemas/ucp.json
index 0067c8a8..4b3d0faa 100644
--- a/spec/schemas/ucp.json
+++ b/spec/schemas/ucp.json
@@ -12,6 +12,11 @@
     "services": {
       "type": "object",
       "description": "Service definitions keyed by reverse-domain service name.",
+      "properties": {
+        "com.example.service": {
+          "$ref": "../services/service_schema.json"
+        }
+      },
       "additionalProperties": {
         "$ref": "../services/service_schema.json"
       }