Information system development (ISD) project is a knowledge-intensive teamwork process which requires members to coordinate their expertise to generate the final outcome. Breakdown or coordination and insufficient knowledge integration have been reported as critical factors which lead to ISD project failure. Most existing coordination literature focus on the effect of administrative coordination mechanisms toward project performance which hints that more efforts are needed to understand expertise coordination and explore ways to improve it. Addressing the above issues, two studies in this dissertation attempt to understand expertise coordination within the IS development team based on social capital perspective. The first study, based on intention-behavior literature, knowledge management research, and Gerwin's (2004) coordination model, investigates relationships among willingness, competence, and actual expertise coordination. The relationships between expertise coordination and teamwork outcomes are also examined. The second study incorporates social capital theory and examines (1) dependencies among three dimensions of social capital and (2) linkage between social capital and expertise coordination. Data collected from more than five hundred information systems project team members was used to test the proposed hypotheses. The analysis results confirmed most of the hypotheses. This dissertation contributes to coordination, project management, and team mental model research through many perspectives. In each study, directions for management practice and future research are discussed.