OBJECTIVES: To determine if different dimensions of outcome expectations are mediators between self-efficacy and exercise among college students. METHODS: Students (n = 290) reported exercise levels, self-efficacy, and expectations using a Web-based questionnaire. Factor analysis was performed to identify dimensions of expectations; regression analyses tested whether each factor mediated the relationship between self-efficacy and exercise. RESULTS: Physical, mental, social, and self-evaluative expectations emerged from the factor analysis, but none was associated with exercise independent of self-efficacy. Self-efficacy, however, was significantly associated with exercise independent of expectations (P < 0.01). CONCLUSIONS: College students' activity expectations are multidimensional, but do not mediate the relationship between self-efficacy and exercise.