Information system development is largely dependent on social interaction and team work. Team composition, team processes, and behavior among, and agile practices used by team members play an important role for the success of information system development projects. Organizational psychology research found team diversity and collective intelligence to be important factors for team performance. In this research-in-progress paper, we propose a model and research design to investigate the effects of team diversity, collective intelligence, interpersonal relationships, and cognitive styles on team efficiency in agile software development. The proposed model combines recent research in the field of organizational psychology with agile information system research to provide a better understanding of the effects of team diversity, collective intelligence, and team efficiency.