Self-theories, or the theories people hold about their own qualities such as abilities, have important consequences for motivation and behavior. Examining self-theories could help us to understand how ability beliefs affect student performance and self-handicapping. The purpose of this study was to assess the impact of self-theories about ability and task difficulty on student performance and use of self-handicapping strategies in sport competitions. In this study, a blocked factorial design was conducted. The subjects were 30 entity and 30 incremental theorists Iranian male students who were divided into four equal sized groups. The first and third groups participated in a 540m track event with a 180-second time limit. The second and forth groups participated in a similar race with a 120-second time limit. After racing, all subjects completed a self-handicapping questionnaire and their performance also was recorded. MANOVA analyses of the resulting data showed incremental students reported fewer self-handicapping strategies for their next race as well as better performance compared with entity participants. These findings were, however, evident in the second competition. Moreover, subjects who participated in the first race, regardless of ability beliefs, did not show significant difference between self-handicapping strategies and performance. The findings highlight that ability beliefs can affect the students’ performance and degree of effort; this emerges when fail probability is high.