Most specialists have concluded that the European Union is not an optimal currency area, because business cycles are not well synchronize, price and wage flexibility is low, and from a fiscal point pf view labor tranfers and migration are not welcome. The expansion of the European Monetary Union involves costs and benefits. The last stage of the process of creating the Eonomic and Monetary Union was the introduction of the single European currency, based on the E.C.U. the European monetary unit used until that date for the calculation of payments within the EU budge. A common currency makes European economies less vulnerable than they were to disruptions in the global monetary system. It improves the capacity of the Community the follow its priorities in which the EU budget. A common currency makes European economies less vulnerable than they were to disruptions in the global monetary system. It improves the Community's ability to pursue its intrinsic economic priorities and goals in a much more autonomous manner.