The main theme of this book is the adaptation process of the new EU member states from Central-Eastern Europe (Hungary and Poland) to the multi-level system of governance in public policy, particularly in the regional and environmental policy areas. The work conceptualizes policy learning and institutional and policy adaptation within the EU system of governance and draws lessons from the experience of previous waves of enlargement-cohesion-countries (Ireland, Portugal and Greece). In doing so, the book makes an important contribution to the literature on the transformation of domestic policy-making structures, as a result of the increasing Europeanization of public policy, as well as on the conceptual tools, explanatory variables and mechanisms determining this process.