Physical activity provides numerous health benefits, but most Canadian youth are not active enough to receive these benefits. The growing trend of inactivity has serious health implications for youth now and into adulthood. A number of theories on motivation suggest that peer relationships influence adolescents’ motivations and behaviour, but little research has explored the influence of peers on physical activity. Meghan McDonough is surveying 500 high school students to determine the role of peer relationships in physical activity motivation and behaviour. She also aims to identify specific elements of peer relationships that are key influences of physical activity motivation and behaviour. Results from the research could contribute to development of programs that motivate youth to participate in physical activity.