The creation of the euro area in 1999 and the subsequent introduction of the euro as a common currency in 2002 were results of a long process of preparation that went back as far as 1947. On the basis of original documents stored in archives in several European countries, this book traces and explains the discussions in the formative years of both the ideas for a monetary union and of the European integration process as such. Its contents reveals that the basic issue to be resolved has remained the same over time: how to organize effective monetary cooperation between ultimately sovereign states. The result of an international cooperative effort of two research institutes, Huygens ING from the Netherlands and the Centre Virtuel de la Connaissance sur l'Europe from Luxembourg, this is the first book to appear on this topic that combines official documents with in-depth archival sources.