Driven by views of teams as dynamic systems with permeable boundaries, scholars are increasingly seeking to better understand how team membership changes (i.e., team members joining and/or leaving) shape the functioning and performance of organizational teams. However, empirical studies of team membership change appear to be progressing in three largely independent directions as researchers consider: (a) how newcomers impact and are impacted by the teams they join; (b) how teams adapt to member departures; or (c) how teams function under conditions of high membership fluidity, with little theoretical integration or consensus across these three areas. To accelerate an integrative stream of research on team membership change, we advance a conceptual framework which depicts each team membership change as a discrete team-level “event” which shapes team functioning to the extent to which it is “novel,” “disruptive,” and “critical” for the team. We use this framework to guide our review and synthesis of empirical studies of team membership change published over the past 20 years. Our review reveals numerous factors, across conceptual levels of the organization, that determine the strength (i.e., novelty, disruptiveness, criticality) of a team membership change event and, consequently, its impact on team functioning and performance. In closing, we provide propositions for future research that integrate a multilevel, event-based perspective of team membership change and demonstrate how team membership change events may impact organizational systems over time and across levels of observation.