World War I was a watershed in modern world history. On the battlefield, millions were slaughtered by chemical warfare, machine guns, and trench warfare—and this senseless bloodletting remains the most enduring legacy of the Great War. Critical to understanding the war’s significance is the often-overlooked emergence of a “modern” dynamic grassroots peace movement that both opposed war and sought to abolish its social causes. Edited by Scott H. Bennett and Charles F. Howlett, Antiwar Dissent and Peace Activism in World War I America presents primary documents, illustrating opposition and resistance to the war and the government’s efforts to promote the war and restrict dissent. This fresh collection highlights the broad range of antiwar sentiment: religious and secular, liberal and radical, pacifist and nonpacifist, including conscientious objection. It also addresses key issues raised by the antiwar movement—particularly dissent in wartime, civil liberties, the meaning of patriotism, and citizen peace activism—that remain vital to understanding the North American history.