Only 30% of college students meet the recommended amount of physical activity (PA) for health benefits, and this number is lower for African American students. Moreover, the correlates of PA may vary by ethnicity. Objective: In the present study, the authors tested the utility of the theory of planned behavior for explaining PA intentions and behavior in Caucasian and African American students. Participants and Methods: Participants were 238 African American (M age = 20.05 years, SD = 2.28) and 197 Caucasian (M age = 19.50 years, SD = 2.28) students who completed a baseline theory of planned behavior questionnaire and a follow-up PA measure 1 week later. Results: Hierarchical regression analyses showed that affective ([beta] = 0.23) and instrumental ([beta] = 0.28) attitudes and perceived behavioral control ([beta] = 0.59) were significantly predictive of intention for the Caucasian students, whereas affective attitude ([beta] = 0.18) and perceived behavioral control ([beta] = 0.56) were significant for African American students. Furthermore, intention ([beta] = 0.33) was the lone significant predictor of PA for Caucasian students, whereas perceived behavioral control ([beta] = 0.23) was the significant predictor of PA for African American students. Conclusions: These data suggest that practitioners may need to consider ethnicity when developing PA interventions for college students based on the theory of planned behavior. (Contains 3 tables.)