This paper examines the evidence between physical activity and cancer in youth populations, both in terms of physical activity as a risk-reduction and rehabilitation behavior. The association between cancer and physical activity as a risk-reducing health behavior is receiving increasing support; however, research on youth participation and subsequent adult cancer incidence is fairly limited, and future research must address numerous design and measurement issues. Specifically, the designs, methods, and measurement vary, highlighting the need for the standardization of measures in future research. Four studies were located that examined physical activity as a means of rehabilitation for youth cancer survivors. All four studies, focusing only on the physical and physiological changes associated with physical activity, found physical activity interventions to be beneficial. Given the positive physical and psychosocial impact that physical activity programs have had in adult cancer survivors, additional research is warranted with children survivors.