The purpose of this study was to explore 188 third through eighth-grade students' patterns of social interaction related to a comprehensive school-based health program, and to investigate relationships between student social capital (i.e., number and frequency of interactions with friends, teachers, and guardians/family members) and teacher implementation. Analyses of survey responses across three time periods revealed that students' patterns of social interaction differed significantly by grade level (elementary versus middle school) and time. There were also significant associations between student social capital and teacher implementation of intervention activities. These results suggest that educational leaders and policy makers attend to social interaction as a lever for intervention success.