The investigators will use a 3-year delayed treatment, cluster randomized controlled trial design with 20 ASPs that serve mostly low-income and minority children (approximately 1300 children ages 6-12yrs) in Columbia, SC and address the following specific aims: Aim 1. Evaluate the impact of a staff-level intervention, a professional development training program focused on core competencies to promote physical activity, on children's physical activity levels; Aim 2. Evaluate the impact of a site-level intervention, a snack modification program that includes a discount buying program, on the quality of snacks served and consumed; and Aim 3. Evaluate the implementation of the staff-level and site-level interventions and identify organizational, staff, and setting characteristics that influence the process of implementing these strategies.