In the past decade, a great deal of attention has been given to the determinants of physical activity in adults. With the growing incidence of obesity among youth and its associated health risks, particularly early onset of Type 2 diabetes, it is imperative to focus more attention on those factors that influence adolescents' adoption and maintenance of physical activity. Ongoing longitudinal epidemiological studies are beginning to suggest that exercise habits established in childhood do not always persist into adulthood (Malina, 2001). Enhanced physical activity during early life, however, may affect lifelong attitudes toward health promotion (Bar-Or, 1994), such as physical activity. These authors are appropriately building on the important body of research on self-efficacy and physical activity in adults being conducted by McAuley & Blissmer (2000) at the University of Illinois at Champaign- Urbana. It is important to see if these findings can be replicated in youth. This research team is proceeding with the important first steps toward the development of tailored interventions for adolescents.