Abstract The concept of implicit organizational timetables suggests that leaders are expected to be older than their followers. However, increased age diversity in the workforce has led to situations in which this is not the case. Expanding on the core tenets of leader categorization theory, the present study establishes the concept of an age-prototypical team characterized by the age of the leader relative to their followers and explores how team age prototypicality influences subsequent observer evaluations of the team. Moreover, this study examines possible boundary conditions and intermediary mechanisms that further explain bias in the evaluation of age-diverse teams. To establish and explore the nature and effect of age-based team prototypes, we conducted 3 independent experimental vignette studies. In Study 1 (n = 590), we establish evidence for age-based team prototypes, by demonstrating a “leaders are older, followers are younger” prototype and further considering the diversity of follower age as a boundary condition for the effects of leader age on ratings of attraction to the team, anticipated team behaviors, and expectations for future success. Then, in Study 2 (n = 686) and Study 3 (n = 782), we extend these results by examining how the perception of team (Study 2) and leader (Study 3) performance cues are influenced by team age composition prototypes. In Study 3, we also consider intermediary attributional mechanisms that explain associations between performance and perceived qualities of the team. Results suggest that prototype inconsistent teams (i.e., teams with younger leaders and older followers) are viewed more harshly in the face of negative performance cues as a function of team composition rather than because of leader or follower attributes individually.