The dependability of volunteers in completing work assignments can impact upon the financial and operational success of major sport events and presents a significant challenge for event organizers. Despite the short-term nature of many events and the apparently manageable level of commitment, volunteers sometimes exhibit less than satisfactory levels of compliance to assigned tasks. Based on the theory of planned behavior (TPB), this study examined the behavioral dependability of operational-level volunteers at major sport events. A preevent and postevent survey protocol was used to gather data from volunteers (n = 391) at five events. The study measured the attitudes and beliefs of event volunteers and their self-reported level of behavioral dependability. Using multiple regression analysis, the study found that a number of attitudinal beliefs about volunteering, subjective norms, and perceived behavioral control predicted behavioral dependability. It was concluded that the TPB was a useful theoretical framework for conceptualizing and predicting the behavior of major event volunteers but the generalizability of these findings was limited because the significant predictors of dependability were not consistent across all of the events studied.