Contributor(s): Nicholas C Garganas | The introduction of the euro posed unique challenges for monetary policy. Some observers took the view that a single monetary policy for all euro-area countries would not succeed because the euro area did not fulfil the pre-requisites of on Optimum Currency Area (OCA). In his lecture Mr Garganas will argue that the traditional way of thinking about OCAs overlooks the fact that the criteria used to judge optimality are, to some extent, endogenous. He will also argue, the experience of the euro area demonstrates that the creation of a monetary union can itself create conditions that are favourable to the well-functioning of the union. Nicholas C Garganas is governor of the Bank of Greece, a member of the Bank's Monetary Policy Committee, a member of the Governing Council and the General Council of the European Central Bank, and a governor of the International Monetary Fund for Greece.