The chapter outlines the EU’s leadership-by-example ambition in climate policy and raises intriguing questions that are addressed in this book. How did the various member-states manage to agree on increasingly ambitious common targets and policies? Have the policies been implemented domestically – and have they served to trigger a transformation towards decarbonization? What are the consequences of these implementation experiences for the adoption of new EU policies to 2030 and beyond? The chapter introduces a pioneering new analytical approach in explaining policymaking, implementation and reform by combining negotiation theory on issue-linkages with theories on EU policymaking and implementation. It offers insights into how climate ambitions can be raised under the most demanding decisionmaking rule – when unanimity is required. Further, the research design and the structure of the book are presented.