diff --git a/api/client-server/old_sync.yaml b/api/client-server/old_sync.yaml
index ccd22816..e3e1ea8a 100644
--- a/api/client-server/old_sync.yaml
+++ b/api/client-server/old_sync.yaml
@@ -384,6 +384,15 @@ paths:
                         allOf:
                           - "$ref": "definitions/event-schemas/schema/core-event-schema/event.yaml"
                   required: ["room_id", "membership"]
+              account_data:
+                type: array
+                description: |-
+                  The global private data created by this user.
+                items:
+                  title: Event
+                  type: object
+                  allOf:
+                    - "$ref": "definitions/event-schemas/schema/core-event-schema/event.yaml"
             required: ["end", "rooms", "presence"]
         404:
           description: There is no avatar URL for this user or this user does not exist.
diff --git a/api/client-server/sync.yaml b/api/client-server/sync.yaml
index f745a11e..8bfdd48a 100644
--- a/api/client-server/sync.yaml
+++ b/api/client-server/sync.yaml
@@ -229,6 +229,13 @@ paths:
                   The updates to the presence status of other users.
                 allOf:
                   - $ref: "definitions/event_batch.yaml"
+              account_data:
+                title: Account Data
+                type: object
+                description: |-
+                  The global private data created by this user.
+                allOf:
+                  - $ref: "definitions/event_batch.yaml"
           examples:
             application/json: |-
               {
diff --git a/changelogs/client_server.rst b/changelogs/client_server.rst
index ac96e482..f5cf318d 100644
--- a/changelogs/client_server.rst
+++ b/changelogs/client_server.rst
@@ -30,7 +30,9 @@
     ``/login`` (`#367 <https://github.com/matrix-org/matrix-doc/pull/367>`_).
   - Make ``origin_server_ts`` a mandatory field of room events
     (`#379 <https://github.com/matrix-org/matrix-doc/pull/370>`_).
-
+  - Add top-level ``account_data`` key to the responses to ``GET /sync`` and
+    ``GET /initialSync``
+    (`#380 <https://github.com/matrix-org/matrix-doc/pull/380>`_).
 
 r0.2.0
 ======