As the number of children affected by obesity increases in the United States, it is necessary to intervene with preventive and intervention techniques that will enact change. Because children spend a significant amount of their time in school, it is of particular interest to target strategies during the school day. Given the recommendations for the total duration and intensity of physical activity children should participate in, recess period is a means of acquiring a portion of this daily recommendation. Contingent reinforcement is a technique that is consistently used in schools to promote behavior change. One of these techniques, group contingencies, has repeatedly been shown to increase desired behavior and decrease inappropriate behavior in schools. In the present study, a multiple baseline design was utilized to investigate the use of interdependent group contingencies in physical activity performance during recess, as measured by pedometers, with one class from each of the third, fourth, and fifth grades at an elementary school. Some of the variability existed in gender- and body mass index-specific (BMI) subgroups, in regard to the effectiveness of the intervention and continued maintenance of increased physical activity levels, following the removal of the intervention. However, the overall results support the use of an interdependent group contingency intervention to increase the amount of physical activity students engaged in during recess.