Team composition literature has established associations of team personality composition and performance in previous research. This study adds to this literature by examining the positive relationship of mean core self-evaluations (CSE) and team performance as well as the moderating effect of team-member exchange (TMX) on this relationship. Using 63 senior business student teams engaged in a management-simulation exercise, there was no support for the main effect of CSE above any variance explained in team performance by mean levels of the Big 5 factors. However, there was strong support for TMX as a moderator where mean CSE was only found to positively relate with team performance when TMX was high. The discussion will detail the results and future directions for research.