One explanation for the development of European integration concerns the actions and perspectives of private and public collective interests at the European level. This work seeks to address questions surrounding the European political economy and asks how and why collective action is formed at the European level. It also considers whether collective action at the transnational level is driven by rational, utility maximizing behaviour or whether explanations couched in social terms are more convincing. Chapters introduce empirical studies in the domains of business, the professions, consumers and environmental interests. By examining group pressure at the European level, this volume aims to reach conclusions which it hopes may contribute to a better understanding of policy making in the European Union.