Organizations increasingly develop projects structured around work teams. This increased emphasis on a team-based structure has resulted in a considerable number of theoretical models aimed at examining the factors that influence team effectiveness. One mediating intragroup process that has recently received significant attention concerns the Transactive Memory System (TMS, Wegner, 1986). TMS relies on the team members? knowledge of distributed expertise, and on how this knowledge is combined within groups. The present article provides a critical review of studies on the transactive memory model and work-group performance. First, a theoretical analysis of the concept of transactive memory and its relationship with similar concepts (team mental models, theory of common ground) is presented. Secondly, the specificities of the transactive memory model are presented and compared with other concepts. Thirdly, studies with dyads, groups or work teams in various educational and professional contexts are presented to provide a better understanding of the functioning of the transactive memory system and the factors underlying its development. Finally, a critical analysis of studies in this domain is made in order to determine future directions for research. The potential theoretical and methodological limitations are presented, notably concerning the problem of conceptualizing and measuring TMS, and the level of analysis (micro- and macro-levels). The potential negative effects of TMS for group performance are then discussed. Finally, the conclusions and practical implications of these studies for work teams are discussed.