Understanding the “human” in human systems integration (HSI) necessitates an understanding of this interplay of the person, team, technology, and system. The goal of this chapter is to provide an overview of the key considerations for HSI relevant to teams, teamwork, and team effectiveness. Given space constraints, we focus on achieving breadth of coverage and identifying core concerns, with pointers to more in depth coverage of relevant topics that are beyond the scope of the chapter. The chapter is structured as follows. We first characterize work teams and identify core considerations for team effectiveness and, thus, HSI. Then, we highlight research findings on team effectiveness organized around the input-process-output heuristic and its more contemporary dynamic representations. Finally, we close with a consideration of critical theory development and research issues necessary for advancing HSI with respect to supporting and enhancing team effectiveness.