Innovations in mobile technology shape how mobile workers share knowledge and collaborate on the go. We introduce mobile communities of practice (MCOPs) as a lens for understanding how these workers self-organize, and present three MCOP case studies. Working from contextual ambidexterity, we develop a typology of bureaucratic, anarchic, idiosyncratic and adhocratic MCOPs. We discuss how variations in the degree of organizational alignment and individual discretion shape the extent to which these types explore and exploit mobile work practices and approach organizational ambidexterity. This article concludes with important strategic implications for managing mobile work and practical considerations for identifying, creating, and supporting MCOPs.