The book “A Guide to EU Renewable Energy Policy” has been published in 2017 to support the understanding of the EU’s renewable energy policy as one of the most ambitious attempts to facilitate a transition towards more sustainable energy systems. It contains key case studies that show how member states have shaped the EU policy, how the EU has affected the policies of its member states and how policies have diffused horizontally. Bernd Hirschl (IÖW) along with three co-authors contributed a chapter to this book concerning the renewable energy policy of Germany in the context of Europeanization. The German Energiewende has been praised as a demanding and relatively successful pioneer strategy towards a more sustainable energy system in the past. However, it has also led to conflicts and disputes in the EU. The chapter asks how the vertical and horizontal interactions between Germany and both the EU and other member states can be appraised. To answer these questions three types of Europeanization are considered: bottom-up, top-down and horizontal.