At the beginning of the twenty-first century, the European Union is an increasingly dense transnational social and political space. More and more non-governmental organisations develop transnational links, which are usually more intensive within the EU, even if they often extend beyond its borders to the wider world. This multi-disciplinary volume explores the importance of these structures, actors and relations for EU and European governance in the context of the theoretical debate about European integration in the social sciences. This book delivers: theoretical chapters examining and discussing the main conceptual perspectives to studying the transnational EU to provide a current overview empirical case studies of transnationalism in practice on transnational party, trade union and police cooperation to transnational education policy-making and transnational consensus-building in EMU governance. This volume will be of great interest to students in social sciences, contemporary history and law.