According to social cognitive theory, self-efficacy influences individual behaviors, such as physical activity engagement patterns, and as a result influences the physical and cognitive benefits that are outcomes from engagement. Children with higher self-efficacy are more likely to participate in physical activity than those with lower self-efficacy. The purpose of this study was to examine the influence of physical fitness, motor competence, gender, age, and ethnicity on physical activity engagement during the summer months with children enrolled in a community-based physical activity program. Specifically, this chapter examines the effects of physical fitness and motor competency on levels of physical activity in children from 16 school districts in the Midwest. Application of social cognitive theory enables researchers to investigate the link between psychomotor achievement and physical activity participation patterns in children. (Contains 3 tables.)