The European Monetary Union: A Critical Evaluation [XAVIER SALA-I-MARTIN] The third stage in the process of European economic and political integration is the monetary union. After the elimination of the barriers to trade and the movement of workers and capitals, now, monetary differences must be eliminated with the creation of the Euro. In this article, Xavier Sala-i-Martin explains the implications of this third stage of European integration. The central point of this article is that the Euro is not only going to bring positive consequences, as «euro-optimists» say, but it is going to involve both favourable and unfavourable aspects.