This book sheds light on the patterns, causes and consequences of the “customization” of European Union (EU) policies. Even if they comply, member states interpret and adapt EU rules in very diverse ways when putting them into practice. We can think of and measure this diversity as a phenomenon of regulatory change along the implementation chain. The book explores what explains customization, and what it means for providing policy solutions to shared problems. It studies the implementation of EU food safety policies in Austria, Germany, France, the United Kingdom and Switzerland using innovative qualitative comparative techniques. After looking at the role of prominent compliance arguments and the “logics of action” for customization, the study assesses how differing degrees of customization affect the success of the implementation. The book provides a new, evidence-based perspective on “gold-plating” and better regulation in Europe for scholars, students and practitioners of policy implementation, European integration and Europeanization alike.