In this book, José Magone addresses the important yet neglected topic of trade unionism in the European Union. He examines two related dynamics: 1) the role of interest groups, and specifically trade unions, in shaping European integration; and 2) the impact of multilevel governance structures on trade unions, particularly in Portugal and Spain. The first part of the book analyzes the concept and reality of multilevel governance in the EU. The second part analyzes the evolution of national systems of interest intermediation and trade union strategies in Portugal and Spain in light of democratization and European integration. The third part assesses the subnational and transnational polices of the Iberian trade union confederations.