While organizations strive to manage the time and attention of workers effectively, the practice of asking workers to contribute to multiple teams simultaneously can result in the opposite. We present a model of the effects of multiple team membership (MTM) on learning and productivity via the mediating processes of individual context switching, team temporal misalignment, and intra-organizational connectivity. These effects are curvilinear, with learning and productivity peaking at moderate levels of these mediating processes.Electronic copy available at: http://ssrn.com/abstract=1474336 do -Manager (Authors, 2007) Over the last century, the primary approach to organizing has shifted from individual work in hierarchical structures, to more team-based work in hierarchical structures, to teambased work in matrix structures, and ultimately to team-based work in multi-team systems (Hatch & Cunliffe, 2006;Hobday, 2000;Malone, 2004;Marks, Dechurch, Mathieu, Panzer, & Alonso, 2005;Scott & Davis, 2006). As these changes have taken place, an increasing amount of responsibility has shifted to individual employees -responsibility for managing their own learning, allocating their own time, and focusing their own attention. This is especially true when employees are members of multiple teams concurrently, with no one manager aware of each employee's full portfolio of work or team commitments. In such situations, individuals may make decisions (about their time, attention, information, etc.) that are completely rational for them, but that do not result in optimal productivity and learning at the team and organizational levels (Schelling, 1978). Conversely, without complete knowledge of individuals' multiple team commitments, teams, managers, and organizations may make reasonable team-and organizationallevel decisions that have very problematic effects for individuals. In this paper, we address this theoretical and practical tension regarding the allocation of time and attention, as well as the flow of information, when people are simultaneously members of multiple teams.Based on our own survey data and surveys by other scholars (Lu, Wynn, Chudoba., & Watson-Manheim, 2003;Martin & Bal, 2006) (Zika-Viktorsson, Sundstrom, & Engwall, 2006). Some surveys place the percent of knowledge workers who are members of more than one team as high as 94.9 percent (Martin & Bal, 2006) and in at least one company (Intel), 28% are on five or more (Lu et al., 2003). In addition, a wide variety of scholars and practitioners have mentioned the commonality of MTM. For example, Gonzalez and Mark's (2005: 143-4) comment is typical: "In fields as diverse as finance, software development, consulting, and academia, we are finding that it is commonplace that information workers are involved in multiple collaborations that occur in parallel. This demands that individuals enact specific efforts to coordinate, manage and track those collaborations." MTM seems especially common (and particularly challenging) in information technology (e.g., Bas...