Since its founding at the end of World War I, the League of Nations has stood at the center of clashing narratives about the twentieth century. For liberals, the League embodies the noble yet unfulfilled vision of Wilsonian internationalism. Realists see its failure as a testament to the durability of power politics. Revisionist historians interpret the League as an institutional tool used by European powers to reconstruct and legitimate their empires. In this major new study, Pedersen portrays the League as an awkward and conflicted undertaking that nonetheless put in motion the decline of imperialism and the spread of national self-determination. Pedersen focuses on the League’s Permanent Mandates Commission, the system established in 1921 to manage the territories in Africa, the Middle East, and the Pacific that Germany, Austria-Hungary, and the Ottoman Empire lost in the war. Many saw the mandate system as a ploy to strengthen British imperial rule. But, as Pedersen writes, the League machinery unexpectedly provided a “platform” for internationalists, humanitarians, nationalists, and others who sought to expose the brutality of imperial rule. It would take decades and another world war to bring about a global system of sovereign independent states. But the League pointed the way.