diff --git a/CHANGES.rst b/CHANGES.rst
index dc9fcf98d..f0bb973dc 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -40,8 +40,10 @@ Application services:
instead their configuration should be saved to a file and listed in the
synapse ``app_service_config_files`` config option. The AS configuration file
has the same format as the old ``/register`` request.
+ See `docs/application_services.rst`_ for more information.
.. _`docs/postgres.rst`: docs/postgres.rst
+.. _`docs/application_services.rst`: docs/application_services.rst
.. _`Registration`: https://github.com/matrix-org/matrix-doc/blob/master/specification/10_client_server_api.rst#registration
.. _`Retrieving Server Keys`: https://github.com/matrix-org/matrix-doc/blob/6f2698/specification/30_server_server_api.rst#retrieving-server-keys
.. _`Application Services`: https://github.com/matrix-org/matrix-doc/blob/0c6bd9/specification/25_application_service_api.rst#home-server---application-service-api
diff --git a/docs/application_services.rst b/docs/application_services.rst
new file mode 100644
index 000000000..07236e62a
--- /dev/null
+++ b/docs/application_services.rst
@@ -0,0 +1,26 @@
+Registering an Application Service
+==================================
+
+The registration of new application services is implementation dependent. In
+synapse you need to create a new configuration file for you AS and add it to
+the list of AS's specified under ``app_service_config_files`` synapse
+config option.
+
+The format of the AS configuration file is as follows::
+
+ url:
+ as_token:
+ hs_token:
+ sender_localpart:
+ namespaces:
+ users: # List of users we're interested in
+ - exclusive:
+ regex:
+ - ...
+ aliases: [] # List of aliases we're interested in
+ rooms: [] # List of room ids we're interested in
+
+See the spec_ for further details on how application services work.
+
+.. _spec: https://github.com/matrix-org/matrix-doc/blob/master/specification/25_application_service_api.rst#application-service-api
+