Structural equation modeling was used to evaluate components within the theories of reasoned action (TRA), planned behavior (TPB), and self-efficacy (SET) for understanding moderate and vigorous physical activity among 1,797 Black and White adolescent girls. Modest to strong support was provided for components of TPB and SET; weak support was provided for components of TRA. Perceived behavioral control was related to vigorous physical activity. Self-efficacy was related to moderate and vigorous physical activity, and it accounted for the effect of intention on physical activity. The observed relationships were similar between Black and White girls. Self-efficacy and perceived behavioral control are independent influences on physical activity among Black and White adolescent girls and warrant study as potential mediators in physical activity interventions.