Oftentimes, evidence-based innovations (EBIs) fail to gain support in systems or fail to scale-up because the developers or implementers of the EBI have not adequately considered the policy environment. In this chapter, implementation is considered from the perspective of public policy and policy makers. The chapter starts by unpacking what is meant (and not meant) by policy and its implementation, sharing a heuristic that is often used to identify the phases through which ideas become policy. This is followed by a brief discussion about the instruments used to make policy and a whirlwind tour of policy implementation models, theories, and frameworks. The chapter then shifts to exploring how research evidence can shape policy, including its implementation, and introduces a framework that can help conduct policy analyses to support better implementation. It concludes with an overview of the approaches that can be taken to support evidence-informed policymaking and provides some examples of such initiatives.