The third volume of The Cambridge History of America and the World covers the volatile period between 1900 and 1945 when the United States emerged as a world power and American engagements abroad flourished in new and consequential ways. Showcasing the most innovative approaches to both traditional topics and emerging themes, leading scholars chart the complex ways in which Americans projected their growing influence across the globe; how others interpreted and constrained those efforts; how Americans disagreed with each other, often fiercely, about foreign relations; and how race, religion, gender, and other factors shaped their worldviews. During the early twentieth century, accelerating forces of global interdependence presented Americans, like others, with a set of urgent challenges from managing borders, humanitarian crises, economic depression, and modern warfare to confronting the radical, new political movements of communism, fascism, and anticolonial nationalism. This volume will set the standard for new understandings of this pivotal moment in the history of America and the world. This volume charts the complex history of American ascent to world power between 1900 and 1945. Brooke L. Blower is Associate Professor of History at Boston University and founding co-editor of Modern American History. Her publications include Becoming Americans in Paris: Transatlantic Politics and Culture between the World Wars (2011). Andrew Preston is Professor of American History and a Fellow of Clare College at Cambridge University. He is the author or editor of nine books, including Sword of the Spirit, Shield of Faith: Religion in American War and Diplomacy (2012).