The European Commission is one of the key European Union (EU) institutions and has been so ever since the early days of European integration. At the same time, its role and the manner in which it exercises its various functions differ widely between the various EU policy domains. This chapter will zoom in on one such specific policy domain, namely the Economic and Monetary Union (EMU). Notably, since the Treaty of Maastricht in 1992, the European Commission has been one of the key players in the elaboration of this specific policy field in all its aspects: in the original setting up and further development of EMU, as an instigator of policy developments, and in applying its rules and regulations. At the same time, the exact nature and content of the role that the Commission plays has strongly evolved over the years. Most recently, the financial and economic crisis that erupted in 2007/2008 and its follow up have profoundly affected the policy area of EMU including the role the Commission plays in the EMU framework.