This paper investigates theoretically and empirically the effect on exchange rates of integrating monetary policy in Europe. It shows that the likely effect will be to generate a tighter European monetary policy (notwithstanding credibility aspects which are not discussed). The argument is that trade disequilibria will be less of a threat to European monetary policy than it is at the moment. Under certain circumstances, which are explored in the text, this could lead to a more volatile euro than we have currently (as a basket of currencies).