The creation of the European Monetary System (EMS) represents one of the landmarks of post-war European economic and political history, and constitutes a fascinating case-study of the formation of an incipient trans- and supranational polity, namely the European Economic Community (EEC). This thesis is the first detailed archivally-based study of European monetary cooperation from the mid- to late 1970s. It is based on an extensive multi-archival and multinational research, including archives of the French, British and German governments, as well as of EEC institutions (Commission, Council of Ministers, Monetary Committee, Committee of Central Bank Governors). This thesis analyses the complex interaction between the numerous actors involved in the process (Finance Ministers, heads of government, central bankers, economic advisors, academic economists) at various levels (domestic, EEC, international), and explains why and how the attention shifts from one level to another. In order to explain the reasons, modes and the extent to which Western European governments were willing to further their monetary cooperation through the EEC, it is essential to go beyond a strictly intergovernmental approach based on 'material interests.' Instead, this thesis delves into a more sophisticated and refined understanding of the process, looking at different modes of governance (transnational, international, supranational), as well as the interplay between different policy areas (transatlantic relations, trade, common agricultural policy) and various connected issues (political, political-psychological, economic, institutional, financial). Contrary to the conventional account of the EMS negotiations, which focuses primarily on the year 1978, this thesis presents a different way of understanding the creation of the EMS by highlighting two longer-term processes: a transnational learning process among a transnational monetary elite, and the impact of the emergence of the European Council on the monetary discussions in the EEC. The interaction of these two features explains why the EMS fundamentally was a fairly trivial technical step, but a tremendously important political one. This thesis therefore shows that more profound trends considerably influenced the inception of the EMS, which remain crucial to a thorough understanding of today's economic and financial world.