The performance of professional sportspeople attracts great interest from the viewing public, team management, coaches, and athletes alike. Contributors to elite performance have been explored across a wide variety of sports, but have generally focused on the physical attributes of athletes, or the differences between athletes across varying levels of competition or compared to non-athletes. This thesis aimed to identify the psychological predictors of elite rugby union player performance through a series of studies. The psychological characteristics of elite rugby union players have only been researched to a limited degree. This was postulated to be in part is due to the relative recent transition to professionalism in 1995, and the time constraints imposed on professional athletes. As such, the access given to players, ex-players, and administrators within professional Australian rugby union for this thesis represent a unique insight into the psychological drivers of elite performance.