Recent trends have identified decreasing levels of physical activity, fitness, and health in preadolescent children. Examining factors, such as physical activity behavior and aerobic fitness that positively influence cognitive health of school-age children are important for improving school performance, maximizing health, and improving the overall functioning of individuals as they progress through the human lifespan. A sample of preadolescent children from the Urbana, Illinois elementary school system will be randomly assigned to a 9- month afterschool program that focuses on either aerobic exercise or wait-list control group to determine the effects of physical activity on basic and applied aspects of cognition. Changes in neuroimaging and behavioral indices of cognitive function and performance on standardized academic achievement tests of mathematics and reading will be examined as a function of participation in the intervention. Preliminary research supports that physical activity is positively associated with basic and applied aspects of cognition, with a stronger relationship for tasks requiring extensive amounts of executive control. However, previous research has mainly focused on older adults, and little research has examined the relationship between physical activity and executive control in children. These findings will provide lifestyle considerations for children to improve their cognitive health across the lifespan.