A chat system includes a chat server and a plurality of chat clients in a network that may be bandwidth constrained. Each chat client is configurable, in response to instructions from the chat server, to operate in either a master mode or a slave mode. In the master mode, a chat client is capable of initiating a chat session. In the slave mode, a chat client is incapable of initiating a chat session and may participate only in a chat session initiated by another chat client operating in the master mode. An invitor user initiates, or adds a member to, a chat session by sending an invitation to an invitee user name at a proxy address at the chat server. If the chat server determines that the invitee is logged on, the chat server forwards the invitation to the invitee at the invitee's network address. If the invitee user accepts the invitation, the invitee client sends a join message to the invitor client, and the invitor client adds the invitee's user name and client network address to a chat member list. Then, the chat session proceeds with the chat member client sending chat input to the master client and the master client sending chat session updates to the member client.