A concern with teams was central to early attempts to grasp the nature of the firm but fell out of favor in later work. We encourage a return to the emphasis on teams but argue that the idea of teams as central to the nature of the firm needs to be grounded in an appreciation of the importance of We frames and group agency. We use converging insights from evolutionary anthropology, cognitive sociology and psychology and work on team agency to develop such a grounding and link it to the issues of the existence, boundaries, and success of firms. Copyright © 2012 John Wiley & Sons, Ltd.