Evaluation policy is of considerable importance, especially in relation to the limited amount of attention it receives as a general topic in the mainstream evaluation literature. Evaluation policies matter for several reasons, among them that they can profoundly affect evaluation practice, they underlie many recent and current controversies about evaluation, and they may be a lever for change that can have far-reaching effects for practice. This chapter gives an overview of several issues regarding evaluation policy, including defining it, identifying possible facets of evaluation policy, describing how it is established, and outlining the potentially greater role for evaluators in shaping the evaluation policies that influence evaluation practice.