Local and state health departments are well-positioned to serve as catalysts for the institutional and community changes needed to increase physical activity across the population. Efforts should focus on evidence-based strategies, including promotion of high-quality physical education in schools, social support networks and structured programs for physical activity in communities, and organizational practices, policies, and programs that promote physical activity in the workplace. Health departments must also focus on land use and transportation practices and policies in communities where the built environment creates major impediments to physical activity, particularly in economically disadvantaged communities disproportionately burdened by chronic disease.