The Young Men’s Christian Association (YMCA) is best known for its athletic and youth programs, a heritage that draws on its origins in 1844 to provide wholesome recreation to urban youth away from the moral decay of industrialized urban living. Before long, that uplift mission found a place in the American Civil War, and soon the Y had spread all over the world by the early twentieth century, and in every major war thereafter as well. The YMCA at War: Collaboration and Conflict during the World Wars is the first collection of scholarship to examine the YMCA’s efforts during the World Wars of the twentieth century, which proved to be a bastion of support to soldiers and civilians around the world. The YMCA deployed hundreds of thousands of its much-vaunted secretaries to support suffering civilians and ease soldiers’ wartime hardships. Joining forces with governments, other civic organizations, and individuals, the Y could be either an indispensable auxiliary or an arms-length nuisance. In all cases, its support had a significant byproduct: for every person it befriended, the Y invariably made an enemy with an opposing party, its patrons, its sponsor, or at times, all three. The YMCA at War offers fresh, timely research in an international and comparative perspective from scholars around the world that evaluates this conflict and collaboration during the World Wars.