In recent years, Instant Messaging (IM) has become one of the most growing online communities, reaching millions of users at home and at work worldwide. As the community expands, assuming more than one identity at the same time becomes a common behaviour of IM users. This paper reports our ongoing research on support for multiple concurrent identities (MCI’s). Our study used an online survey and face-to-face interviews to identify user needs in supporting MCI’s in IM. The study has identified five themes including single nickname, multiple avatars, multiple statuses, boundary control and interoperability. Reflecting on these themes, we propose a framework of MCI support in IM.