The Heart Healthy Kids (H2K) program examines peer mentoring and physical activity of grades 4, 5, and 6 students (n=808 children from 10 schools). This sub-study qualitatively explored the peer mentoring experience, using the social ecological model to examine the experience from multiple perspectives. A qualitative description design was used, with a phenomenological approach to data analysis. Three focus groups were conducted with 17 children (5 male, average age: 10.6 years) at 3 of the H2K intervention schools. Six additional individual interviews were conducted with 1 parents and 1 teacher from each focus group school (all female). Thematic analysis was conducted. Emergent themes included that peer mentors were perceived as “encouragers of physical activity”, “helpers and supporters”, “organizers and administrators”, and “expanders of social networks”. Results suggest that reframing physical activity programs to promote physical activity in the context of fun, unstructured, social engagement, especially those that employ peer mentoring, may be more successful. This research contributes to development of future programs and research, and knowledge of the applicability of peer mentoring in influencing child physical activity levels.