diff --git a/src/as2.lisp b/src/as2.lisp
index fc13400..49aaf46 100644
--- a/src/as2.lisp
+++ b/src/as2.lisp
@@ -124,3 +124,12 @@
   height
   width
   preview)
+
+(defclass activity (object) ())
+(define-property-methods activity
+  actor
+  object
+  target
+  result
+  origin
+  instrument)