The literature on optimal currency areas identifies the symmetry of disturbances and the speed with which economies adjust as key criteria affecting the decision of whether to form a monetary union. This paper uses structural vector autoregression techniques to examine these issues for three regions: Western Europe, the Americas, and East Asia. The results suggest three country groupings that best satisfy these criteria: Northern Europe (Germany, France, the Netherlands, Belgium, Denmark, Austria, and possibly Switzerland); Northeast Asia (Japan, Taiwan, and Korea); and Southeast Asia (Hong Kong, Singapore, Malaysia, Indonesia, and possibly Thailand).