Information system development is largely dependent on social interaction and team work. Team processes and behavior among, as well as agile practices used by, team members play an important part for the success of information system development projects. To reap benefits from the highly interactive and social practices of agile information systems development, team members need to feel save to interact and speak freely with one another. In this paper, we propose a model that conceptualizes the effects of psychological safety and agile practices on performance in agile information systems 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 team-level effects at play in agile information systems development and is preliminary supported by case studies conducted in two large insurance companies and a small-to-medium sized software development company.