This chapter revisits the turning points in the evolution of the global economic system in the century since 1919, emphasizing the evolution of the international monetary system and policy cooperation/coordination. We identify four disruptions and examine how each prompted changes in the underlying ideology about how the international monetary system should be organized. First, the eruption of the First World War confirmed the end of the First Globalization. Second, the Second World War prompted the creation of a new managed system at Bretton Woods. Thirdly, in the 1970s the Bretton Woods consensus finally gave way to a new non-system dominated by floating exchange rates for the major world currencies and heralded the acceleration of financial integration of global markets. The final turning point is the 2007–8 global financial crisis, which has provoked an echo of the threats that Keynes identified for the global economy in 1919. Each turning point was characterized by different forms and motivation of cooperation, how rules (either implicit or explicit) were designed and implemented, and the crucial importance of the historical context. Finally, the chapter explores how the dominant interpretations of the past shaped policy reactions in the present and concludes with some lessons for today.