The European Union, Germany and the United Kingdom have been characterized as leaders in policy evaluation, including in the area of environment and climate policy. The first approaches to evaluation emerged in the 1980s and 1990s, as the EU started dispersing funding to new Member States and various types of reforms demanded more efficient and effective government action. Unpacking such developments, this paper focuses on the historical development of policy evaluation at the EU level, as well as in Germany and in the United Kingdom. It focuses particularly on the actors and institutions that have advanced evaluation, especially the area of environment and climate policy evaluation. The chapter closes with what we know about evaluation in these three jurisdictions and the three foundational ideas of polycentric governance, namely self-governance, context and interactions between governance centers. It provides the starting point for the empirical exploration in this book.