The Economic and Monetary Union comprising eleven member countries which constitute the Eurozone has been in effect since January 1, 1999. In 2001, it will be joined by Greece. Further expansion of the euro area is to be expected, although the exact dates for accession by Denmark, Britain and Sweden are difficult to predict at this stage. Moreover, the CEE countries now aspiring to the European Union are also interested in the full membership of the Economic and Monetary Union. How quickly these countries will be integrated with the EU in terms of a common currency will depend on their ability to adjust to functioning in a single currency environment. Besides, the development of the euro area will be determined by the general progress of integration processes within the Union. The key question is whether the national governments will be interested in strengthening their cooperation, with a view to transform the Union into a true federal state.