This volume is part of a series on 20th-century world history, which aims to provide greater understanding of people, cultures and events and the part they have played in the century's major events. This work on international co-operation focuses on the League of Nations and the UN. The main institutions of each one are described, along with the key issues against which their relative failures and successes can be assessed. The author stresses the interplay between the activities of the international organizations and the wider context of global tensions especially in the 1930s and the years of the Cold War.