This study, conducted by a team of economists from the Asian Development Bank, academics, and personnel from Cambodia, the Lao People's Democratic Republic, and Viet Nam (the CLV countries) finance ministries and central banks, explores the issues of multiple currencies and regional monetary cooperation among the economies of the Association of Southeast Asian Nations (ASEAN) in the context of increasing regional economic interdependence. It reviews the main issues related to the monetary and exchange rate policy decisions taken by CLV national authorities, and discusses the options and opportunities available for enhancing monetary and financial stability in the ASEAN region.