This policy brief explains various aspects of an issue that will be at the centre of the agenda at the upcoming G20 summit in Washington: the reform of the regulation of international financial markets. Current debates are focused on the regulation of international banking, derivatives, credit rating agencies, accountancy, hedge funds and offshore financial activity. This brief maps out recent regulatory initiatives in these areas as well as the actors and political coalitions advocating further reform. It concludes by highlighting the importance of the G20 summit in responding to the high expectations it has generated and centrifugal pressures in the international financial system.