The European Union (EU) has clearly made a difference for Civil Society Organizations (CSOs). EU officials and European political entrepreneurs have been crucial in the promotion of funding and access opportunities, but they have been proven to have little capacity to create CSOs from scratch or to use CSOs too bluntly for their own purposes. This book brings Europeanization studies closer to society by providing a sociologically-informed analysis, which challenges current assumptions and highlights neglected areas of study. It also addresses many of the methodological challenges in the empirical study of the Europeanization of interest groups, including a comparative analysis over a long time period. The book provides a comparison across three countries, France, UK and Spain, and two policy sectors, international solidarity and social CSOs.