In the highly globalized world economy of our times, where markets are tightly integrated, setting domestic economic policy with a view simply to keeping one’s house in order is no longer optimal. New responsibilities follow for each member of the community of countries from the recognition that the action by one may affect the others. These mutual responsibilities form the core of what we call the ‘Good Global Citizen’ remit of the IMF, a reformed framework for international economic and financial cooperation. This study identifies the new responsibilities, and defines and articulates the rules under the proposed remit.