Monetary union is the final stage in economic and financial integration among countries, in the specific case analyzed in the present paper among the countries participating in the Treaty of Maastricht providing for the implementation of such a union as the ultimate objective of the convergence toward a unified Europe. Membership in such a union would require the adoption of a common currency and its circulation as a single legal tender (or the final and irrevocable pegging of exchange rates among the currencies of the participating countries), as well as the conduct of common monetary (including foreign-exchange) policy.