Supporting awareness plays a prominent role in facilitating natural and effective communication in Instant Messaging (IM). This paper reports our empirical study of awareness in IM, using an online survey and face-to-face interviews to identify user needs for awareness support. The study has identified three themes, including awareness of multiple concurrent conversations, presence awareness of a group conversation, and visibility of moment-to-moment listeners and viewers. The study showed that these three types of awareness are necessary but have been either ineffectively supported or ignored by current IM systems. Drawing on these findings, we have designed three awareness features to support these three categories of awareness. Conversation Dock provides awareness of multiple conversations; Group List provides presence awareness in a group chat by showing who are no longer in the group chat and who are going to join the chat; and Track View provides awareness of in-progress listeners in voice conversations and in-progress viewers in video conversations.