Economic and Monetary Union (EMU) exemplifies in a strikingly vivid manner the enormous extension of the policy scope of the EU over the last thirty years, the EU's asymmetric and ‘fuzzy’ institutional arrangements for handling policies, and the stresses associated with EU enlargement and concomitant increased diversity. In other words, it is bound up in the complex interaction between processes of ‘broadening’, ‘deepening’, and ‘widening’. In terms of scope, EMU is ‘nested’ within and alongside a range of policies: from the single market and competition policy, through the Lisbon process and employment and labour-market policies, to cohesion policies. This article focuses on the policy core of the EMU, which comprises fiscal policy coordination, represented by the Stability and Growth Pact and the single monetary policy of the European Central Bank.