This thesis focuses upon three distinct episodes in the development of European foreign policy co-operation : 1. The Fouchet Negotiations of 1961-62; 2. The Luxembourg Report of 1970; 3. The Single European Act of 1986. In the context of these episodes a number of consistent themes are apparent. Firstly, the inclusion and participation of the UK is seen to be of crucial importance to the legitimacy and credibility of foreign policy co-operation. Secondly, the gradual but perceptible decline of French influence among its European partners. Thirdly, the importance of the role of the Western European Union in the development of foreign policy co-operation. This thesis develops the view that evolution of European foreign policy co-operation should not be viewed in the context of a struggle between Supranational and Intergovernmental visions of European integration. It concludes that there is among member states a broad underlying consensus with respect to the fundamental character of a European foreign and defence identity.