In May of 1919, women from around the world gathered in Zurich, Switzerland, and proclaimed, "We dedicate ourselves to peace!" Just months after the end of World War I, the Womens International League for Peace and Freedom--a group led by American progressive Jane Addams and comprising veteran campaigners for social reform--knew that a peaceful world was essential to their ongoing quest for social and economic justice. Alan Dawley tells the story of American progressives during the decade spanning World War I and its aftermath. He shows how they laid the foundation for progressive internationalism in their efforts to improve the world both at home and abroad. Unlike other accounts of the progressive movement--and of American politics in general--this book fuses social and international history. Dawley shows how interventions in Latin America and Europe affected domestic plans for social reform and civic engagement, and he depicts internal battles among progressives between unabashed imperialists like Theodore Roosevelt and their implacable opponents like Robert La Follette. He draws a contrast between Woodrow Wilson's use of force in exporting American ideals and Addams's more cosmopolitan pursuit of economic justice and world peace. In discussing the debate over the League of Nations within the context of turbulent domestic affairs, Dawley brings keen insight into that complicated moment in American history. In striking and original ways, Dawley brings together domestic and world affairs to argue that American progressivism cannot be understood apart from its international context. Focusing on world-historical events of empire, revolution, war, and peace, he shows how American reformers invented a new politics built around progressive internationalism. Changing the World retrieves the progressive tradition in American politics and makes it available to contemporary debates. The book speaks to anyone seeking to be both a good citizen within the nation and a good citizen of today's troubled world.