This article explores antecedents and outcomes of group-level person-group (PG) fit perceptions. Based on the categorization-elaboration model (CEM), the authors explain how social category (gender and age) and informational diversity (education and work experience) in work teams may elicit supplementary and complementary fit perceptions among team members. The authors then examine two mechanisms through which perceived fit might influence leader-rated group performance. Supplementary fit (similarity on values) is hypothesized to work through a relationship-oriented mechanism by influencing social cohesion. Complementary fit (abilities meet job demands) is expected to work through a task-oriented mechanism by influencing the teams’ transactive memory systems. Participants include employees (N = 1,101) and leaders (N = 116) from 116 work teams in two private firms located in Seoul, Korea. Results generally support the hypothesized relationships, with the task-oriented mechanism being more influential of group performance. Post hoc analyses also suggest that a superordinate perception of PG fit may underlie the assessments of the more specific types of fit. The authors conclude that diversity within groups influences an emergent perception of group-level fit, having related supplementary and complementary components, which in turn are associated with group-level outcomes.