Human beings act together in characteristic ways, and these forms of shared activity matter to us a great deal. Think of friendship and love, singing duets, dancing together, and the joys of conversation. And think about the usefulness of conversation and how we frequently manage to work together to achieve complex goals, from building buildings to putting on plays to establishing important results in the sciences. With Shared Agency, Michael E. Bratman seeks to answer questions about the conceptual, metaphysical and normative foundations of our sociality and to establish a framework for understanding basic forms of sociality. Bratman proposes that a rich account of individual planning agency facilitates the step to these forms of sociality. There is an independent reason - grounded in the diachronic organization of our temporally extended agency - to see planning structures as basic to our individual agency. Once these planning structures are on board, we can expect them to play central roles in our sociality. This planning theory of individual agency highlights distinctive roles and norms of intentions, understood as plan states. In Shared Agency Bratman argues that appeals to these planning structures enable us to provide adequate resources for an account of sufficient conditions for these basic forms of sociality. Shared agency emerges, both functionally and rationally, from structures of interconnected planning agency.