European Integration Theory provides an overview of the major approaches to European integration, from federalism and neofunctionalism to liberal intergovernmentalism, social constructivism, normative theory, and critical political economy. Each chapter represents a contribution to the ‘mosaic of integration theory’. The contributors reflect on the development, achievements, and problems of their respective approach. In the fully revised and updated third edition, the contributors examine current crises with regard to the economy, migration, and security. Two concluding chapters assess, comparatively, the strengths and weaknesses of each approach, and look at the emerging issues. The third edition includes new contributions on the topics of regional integration, discourse analysis, federalism, and critical political economy.