This book argues for a new conceptual framework to understand the monetary side of regional economic integration. It analytically distinguishes between North-South monetary coordination, which involves an international key currency, and South-South arrangements between economies all marked by external indebtedness and the resulting macroeconomic instabilities ('original sin'). In this light, the first part of the book analyzes different types of monetary coordination, ranging from ad hoc exchange rate policy agreements to projects of a common supranational currency, and asks for the potential stabilization gains for developing countries. This conceptual framework guides selected regional case studies, including the Euro candidates of Eastern Europe, the CFA zone in Francophone Africa, the common currency zone of Southern Africa, the ASEAN+3 countries of Asia and Mercosur and NAFTA in Latin America. The innovative conceptual approach and the thorough empirical studies make this book a major contribution to understanding the monetary dynamics and perspectives of regional integration.