Collective Action in the European Union is the first ever systematic investigation of collective action issues at the EU level itself. Bringing together an impressive array of EU and interest group scholars to investigate a key issue in European political economy, this study considers whether collective action is driven at the European transnational level by rational, utility maximising behaviour, or whether explanations couched in social terms are more convincing. The first chapters identify and address wider issues in transnational collective action. Later chapters apply these issues to specific domains, such as business, the professions, consumers, and environmental interests. Many of these chapters introduce fresh empirical evidence, including original surveys of the constituency of Euro groups and of national groups who operate at the European level.