The awareness of others' activities has been widely recognized as essential in facilitating coordination in a team among Computer-Supported Cooperative Work communities. Several field studies of software developers in large software companies such as Microsoft have shown that coworker and artifact awareness are the most common information needs for software developers; however, they are also two of the seven most frequently unsatisfied information needs. To address this problem, we built a workspace awareness tool named TeamWATCH to visualize developer activities using a 3-D city metaphor. In this paper, we discuss the importance of awareness in software development, review existing workspace awareness tools, present the design and implementation of TeamWATCH, and evaluate how it could help detect and resolve conflicts earlier and better maintain group awareness via a controlled experiment. The experimental results showed that the subjects using TeamWATCH performed significantly better with respect to early conflict detection and resolution.