The importance of teamwork in Information Systems Development (ISD) practice and education has been acknowledged but not studied extensively to date. This paper tests a model of how groups participating in ISD projects perform and examines the relationships between some antecedents of this performance based on group research theory well established in the organizational behavior literature. Most modern organizations require individuals to work in teams to perform their tasks. Information systems development teams, advertising teams, and new product development teams are only a few examples from the business community. The group work environment creates challenges for the group members that may affect the group's performance. The relevance and importance of group performance and its antecedents has been addressed in other areas of research: in Social Cognitive Theory (Bandura, 1997), and group related research theories (Festinger, Schachter, & Back, 1950; Gibson, 1999; Salas, Rozell, Mullen, & Driskell, 1999; Woodman & Sherwood, 1980). The importance of group work is also recognized within IS practice (Gorla & Lam, 2004; Sawyer, 2004) and IS education (Ford & Morice 2003; Gackowski, 2003; Whatley, 2004) as organizations look for ways to improve group performance (Lee & Farh, 2004; Trimmer, 1997; Van Der Vyer & Lane, 2003). For example, organizations are looking for products, such as groupware software and web portals, that allow for online collaborative work, in turn helping them to think more quickly, to reduce production costs, and to get those products to the market sooner. Another example are IS projects that involve group work is Information Systems Development (ISD) which often involve systems analysts and designers working in a group setting, either face-to-face or through electronic collaboration. As a result, organizations need to have an in-depth understanding of what encourages groups to perform better (Phan, Vogel, & Nunamaker, 1995; Yang & Tang, 2004) regardless of the medium of communication. Moreover, Alavi, Wheeler, and Valacich (1995) suggest that this issue needs to be incorporated into IS and business education. Therefore, the goal of this study is to identify, define and measure the determinants of group performance in ISD projects. To meet this need, a comprehensive research model is developed based on small-group research and IS literature. First, this research reviews the theoretical foundations upon which it is built. We, then, discuss the research model and hypotheses, and describe the research methodology. Finally, we present the results and discuss the practical and research implications of these results. The results suggest that team building has a positive effect on both task and social cohesion. Group performance is influenced by task cohesion. Our findings make several contributions to information systems literature. First, our findings extend the existing literature on group research by exploring the process by which group performance is realized. Second, they demonstrate the applicability of small-group research to information systems development groups. Thirdly, they provide insights for researchers and practitioners to enhance their understanding of various determinants of group performance. Finally, our findings are useful to educators in (ISD) field who incorporate group work into their course design. (Contains 2 figures and 7 tables.)