The book advances the state of the European Union’s policy theory by taking stock of seven promising frameworks of the policy process, systematically comparing their limitations and strengths, and offering a strategy to develop robust research agendas. Frameworks may constitute competing policy explanations depending on assumptions they make about EU institutional and issue complexity. The frameworks include detailed analyses of multi-level governance, advocacy coalitions, punctuated equilibrium, multiple streams, policy learning, normative power Europe, and constructivism. Besides generating a fertile dialogue that transcends the narrow confines of EU policy, contributions highlight the value of intellectual pluralism and the need for clear and rigorous explanations of the policy process. This book was published as a special issue of the Journal of European Public Policy.