diff --git a/docs/api/index.rst b/docs/api/index.rst
index a79f2bae..bede978b 100644
--- a/docs/api/index.rst
+++ b/docs/api/index.rst
@@ -4,6 +4,15 @@
 API reference
 *************
 
+.. warning:: API stability
+
+    Only APIs documented here are public and open for use by Mopidy
+    extensions. We will change these APIs, but will keep the changelog up to
+    date with all breaking changes.
+
+    From Mopidy 1.0 and onwards, we intend to keep these APIs far more stable.
+
+
 .. toctree::
     :glob: