The current invention discloses methods and devices for adding a new member to a group, e.g. a chat group associated with a chat program. The new member may be added through a barcode-scanning process or an existing-member-invitation process. After the new member is added to the chat group, a server may send notification messages to mobile devices associated with the existing members of the group. The contents of the notification messages may vary based on the processes by which the new member is added, the number of existing members, and the direct-contact relationships the new member has with the existing members. The current invention provides simplified methods and devices for adding the new member, avoiding cumbersome operations and protecting member privacy at the same time.