The Sixties were a decisive period in the history of European integration. The different concepts of European unification were clashing more violently than ever, leading to the confrontation with French President Charles de Gaulle and to the crisis of the "Empty Chair". However, of the crisis led to a new basic consensus, which was to shape the structure of the European Community lastingly. The socalled "Compromise of Luxembourg" in early 1966 opened the way to more confidence in a common future of the Europeans. With the acceptance of the Harmel Report, a workable compromise was reached on the aims and structure of the Western alliance. The Hague Summit in December 1969 set the course for the membership of Great Britain and further applicants, for a new form of politicial cooperation and for the Monetary Union as well. This volume, issued from the seventh Research Conference of the European Community Liaison Committee of Historians held in Essen in November 1999, offers for the first time a comprehensive view of the crises and compromises in the European project of the Sixties. Leading experts from 11 countries are presenting the main results of their most recent research in the archives of the European Union.