Although performance expectancies have been shown to be important mediators of achievement behavior, few specific determinants of personal expectancies have been identified, the ecological validity of previous results is limited, and factors influencing group performance expectancies have not been determined. Therefore, the purpose of this field study involving 11- and 12-year-old male soccer players was twofold. First, we examined specific intrapersonal and situational factors influencing players' pregame personal and team performance expectancies. Second, we investigated the effects of winning and losing a competitive soccer game on players' postgame team expectancies involving a hypothetical rematch with the identical opponent. The pregame findings revealed that (a) the intrapersonal factors of ability and self-esteem were related to personal performance expectancies while competitive trait anxiety was not, and (b) the situational factors of past win-loss record and a prior game win or loss against the same opponent influenced team performance expectancies. The postgame findings revealed that future expectancies were affected by the interactive effects of game win-loss and self-esteem.