Good team players are often defined in trait terms; that is, they are described as dependable, flexible, or cooperative. Our goal is to examine the relationship between team member personality traits and team effectiveness. However, to understand the effects of personality on team performance requires greater specificity in how personality is described and in how team effectiveness is described. A hierarchical model of team member personality is presented that defines higherlevel personality traits and specific facets relevant to team performance. Next, a classification of the core teamwork dimensions underlying effective team performance is presented. Finally, predictions are derived linking team member personality facets to specific teamwork requirements.