Policies have played an important role in improving population health throughout history. Policies can create changes for broad populations and be sustained over time in ways that individual strategies and interventions cannot. This chapter discusses developing policy and environmental interventions. It helps the reader to understand the advantages of policy interventions for promoting physical activity (PA). The chapter applies the levels of the PA policy research framework to at least one policy-related issue. It also applies the five interrelated steps of policy development to at least one policy-related issue. The chapter explains the importance of the multiple-streams framework for promoting PA policies. It finally synthesizes the reasons for policy evaluation. Given the significant role that PA plays in health promotion and disease prevention, policies and environmental changes have emerged as recommended strategies to increase PA and decrease sedentary behavior.