An intrinsically motivated behavior is one undertaken and enjoyed for its own sake, apart from external controls or ends. Expectancies are competence cues which focus on an individual's ability without providing objective information for ongoing comparison and competence development. This study focused on the role of affect in mediating the effects of externally communicated expectancies on intrinsic motivation. College students (N=84) were given positive, neutral, or negative mood inductions prior to an expectancy manipulation. Expectancy subjects were given a performance prediction; No Expectancy subjects were not. All subjects worked on two sets of puzzles separated by a midgame questionnaire. Intrinsic motivation was measured during a free choice period. The results showed that arousal emerged as the critical mediator of task interest. Both happy and sad manipulations significantly altered arousal, and arousal appeared to have eliminated typical expectancy effects among both high and low achievers. These findings support a model of intrinsic motivation in which the arousal component of affect is a critical process variable. (NB)