This study examined the relationships between athletes' perceptions of coaching effectiveness, based on the coaching efficacy model, and their effort, commitment, enjoyment, self-efficacy, and prosocial and antisocial behavior in rugby union. Participants were 166 adult male rugby-union players (M age = 26.5, SD = 8.5 years), who completed questionnaires measuring their perceptions of four dimensions of coaching effectiveness as well as their effort, commitment, enjoyment, self-efficacy, and prosocial and antisocial behavior. Regression analyses, controlling for rugby experience, revealed that athletes' perceptions of motivation effectiveness predicted effort, commitment, and enjoyment. Further, perceptions of technique effectiveness predicted self-efficacy, while perceptions of characterbuilding effectiveness predicted prosocial behavior. None of the perceived coaching effectiveness dimensions were related to antisocial behavior. In conclusion, athletes' evaluations of their coach's ability to motivate, provide instruction, and instill an attitude of fair play in his athletes have important implications for the variables measured in this study.In the general coaching effectiveness literature, effective coaching behaviors are considered those that result in positive outcomes for athletes; examples of these outcomes are performance, enjoyment, self-esteem, and perceived ability (see Horn, 2002). Thus, effective coaches are generally those, who, through their behaviors, produce positive outcomes in athletes. However, models of coaching effectiveness also point to the central role of athletes' perceptions of coaching behaviors in affecting athlete-related outcomes (Horn, 2002;Smoll & Smith, 1989). Thus, in studies of coaching effectiveness, the investigation of athletes' perceptions of coaching behavior is important. In the current study, coaching effectiveness was operationalized based on the coaching efficacy model and athlete-related outcomes specified in this model were examined. The construct of coaching efficacy was developed by Feltz and colleagues, who used Bandura's (1986Bandura's ( , 1997 theory of self-efficacy as their guiding framework, and defined coaching efficacy as the extent to which coaches believe that they have the capacity to influence the learning and performance of their athletes (Feltz, Chase, Moritz, & Sullivan, 1999). Coaching efficacy has been described as multidimensional in nature, consisting of four dimensions: motivation, game strategy, technique, and character building . Motivation efficacy is the confidence coaches have in their ability to influence the psychological skills and states of their athletes. Game strategy efficacy is the coaches' confidence in their ability to coach and lead their team to a successful performance during competition. Technique efficacy refers to the coaches' efficacy beliefs about their instructional and diagnostic skills. Finally, character-building efficacy concerns the coaches' beliefs in their ability to influence their athletes' personal development...