The introduction of the euro has been a milestone in the ongoing process ofEuropean integration, as ECB President Duisenberg put it in his statementbefore the European parliament on 5 July 2000. In this article I shall discusstwo topics. First, the reason why monetary integration has come to playsuch a central role in that process. And second, whether economic andmonetary union will turn out to be durable if participating countries arenot sufficiently homogeneous and if it is not based on a