This study evaluated the effectiveness of a student-led physical activity intervention that incorporated pedometers and cognitive-behavioral strategies. Undergraduate students (N = 117) enrolled in upper division exercise and sport science courses recruited participants. Participants in the cognitive-behavioral intervention condition received weekly mentoring from students on strategies to foster self-regulation, whereas those in a minimal intervention control condition (i.e., pedometer and self-monitoring) did not. All volunteers wore a pedometer for 6 weeks, maintained a step-count log, and completed physical activity and barrier self-efficacy measures pre- and postintervention. Repeated measures analysis of variance revealed that intervention condition participants increased their steps more so than those in the control condition, F(5, 570) = 10.1, p less than .0001, starting at Week 3, with effect sizes in the moderate range. Intervention condition participants also reported increased physical activity self-efficacy, whereas those in the control condition did not, F(1, 77) = 5.6, p less than 0.03, Cohen d = 0.47. There were no significant changes in barrier self-efficacy for either group. Overall, these findings suggest a student-led cognitive-behavioral pedometer intervention results in more favorable changes in step counts and physical activity self-efficacy than simply wearing a pedometer and self-monitoring step counts. (Contains 1 note and 4 tables.)