Objective: To identify determinants of participation in moderately, and vigorously intense physical activity among African-American and Caucasian adolescent females. Methods: Participants (n=626 African-American; n=226 Caucasian) completed an 81-item questionnaire that assessed influences on physical activity and a 1-week recall of physical activity. Multiple regression was used to identify correlates of physical activity. Results: Differences in psychosocial predictors of physical activity were noted by type of activity and ethnic group. Self-efficacy and school sport participation were robust predictors of physical activity. Conclusion: Different strategies may be appropriate when promoting physical activity to African-American and Caucasian female adolescents.