diff --git a/Private-Group-Sharing-Client.md b/Private-Group-Sharing-Client.md
index e73b688..3250fb0 100644
--- a/Private-Group-Sharing-Client.md
+++ b/Private-Group-Sharing-Client.md
@@ -56,6 +56,8 @@ Peer state machine:
 
 [peer-state-machine.odg](/uploads/5ce3b0b86499171236512b4136ddc1d7/peer-state-machine.odg)
 
+"Member announcement" in the peer state machine indicates receipt of the contact's [join message in the private group](Private-Group-Client#message-types), demonstrating that the contact is a member.
+
 ### Validity policy
 
 * An invite message is valid if it is well-formed, is sent by the group creator, and has a valid signature from the group creator.