There are two important trends in organizations today: 1) the increasing use of teams and 2) the increasing diversity in the workforce. The literature is in tune with these organizational trends, evidenced by a dramatic increase in research on team performance and the effects of diversity. However, there are still contradictory findings of the effects of team diversity on team processes and outcomes. To shed light on these inconsistencies, the cognitive construct of team mental model is introduced as a mediator of the relationship between team cognitive diversity and team performance. Team mental model is an emergent cognitive state that represents team members' organized understanding of their task environment (e.g., Klimoski & Mohammed, 1994) and has been shown to improve team performance (e.g., Edwards, Day, Arthur, & Bell, 2006; Mathieu, Heffner, Goodwin, Salas, & Cannon-Bowers, 2000). Specifically, with a sample of 94 student teams I investigated how team cognitive diversity affects team mental model similarity and accuracy, and through them, team performance. In addition, I examined team information processing mechanisms as moderators of the relationships between team cognitive diversity and team mental model similarity and accuracy. The results suggest that cognition at the team level plays an important role in the effective functioning of decision making teams. Specifically, the combination of team mental model similarity and accuracy predicts levels of team performance and information integration is an important moderator linking cognitive style diversity to task mental models, team processes, and team performance. The research model developed and tested seeks to advance understanding of the “black box” linking team diversity to team outcomes (Lawrence, 1997) and to provide guidance to managers leading cognitively diverse teams.