diff --git a/about/index.md b/about/index.md
index ca49791..4af9154 100644
--- a/about/index.md
+++ b/about/index.md
@@ -181,6 +181,12 @@ Social networks
 - [LinkedIn](http://www.linkedin.com/in/barnes1463)
 
 
+Professional societies
+----------------------
+
+- [Association for Computing Machinery (ACM)](http://member.acm.org/~ian.barnes)
+
+
 Colophon
 --------