Objective: To examine the degree to which the use of selected theoretically derived self-regulation strategies (eg, goal setting) could predict adolescents' self-reported leisure-time physical activity behavior. Method: Two hundred thirty-three (M age = 15.88) high school students completed measures assessing their self-regulation strategy use and their level of physical activity. Results: Correlational analysis showed self-regulation strategy use was significantly related to adolescent physical activity. Regression analysis also revealed that goal setting and a causal attribution dimension accounted for 10.7% of the variance reported in adolescents' physical activity. Conclusion: There is a significant positive relationship between adolescent leisure-time physical activity and certain theoretically derived self-regulation strategies.