This book contains the proceedings of a conference held in Copenhagen on December 10th, 2004 on the occasion of Niels Thygesen's 70th birthday. The authors of this book are colleagues and friends of Niels Thygesen. They have all made important contributions to European or international monetary cooperation, either through the insights gained via their academic research, or as key policy makers. The book provides an overview of the historical and theoretical background for monetary union in Europe, an extensive assessment of the experience with the first six years of the Eurosystem, and a discussion of the "unfinished business" of the EMU, including the fiscal framework and the framework needed to secure financial stability. The book ends with a discussion of the implications of Europe's experience with monetary unification for other regions.