In 1993, Czechoslovakia experienced a two-step breakup. On January 1, the country disintegrated as a political union, while preserving an economic and monetary union. Then, the Czech–Slovak monetary union collapsed on February 8. This paper analyzes the economic background of the two breakups from the perspective of the optimum currency area literature. The main finding is that the Czech and Slovak economies were vulnerable to asymmetric economic shocks, such as those induced by the economic transition. In particular, the stability of Czechoslovakia was undermined by the low correlation of permanent output shocks, low labor mobility, and higher concentration of heavy and military industries in Slovakia. J. Comp. Econom., December 1999, 27(4), pp. 753–781. Center for European Integration Studies (ZEI), University of Bonn, Walter-Flex-Strasse 3, 53113 Bonn, Germany, and Center for Economic Research, Tilburg University, Netherlands; Academia Istropolitana Nova, Bratislava, Slovakia, Central European University, Nador u. 9, 1051 Budapest, Hungary, and Center for European Integration Studies (ZEI), University of Bonn, Bonn, Germany; Institute for Advanced Studies (IHS), Stumpergasse 56, 1060 Vienna, Austria.