As a result of the cooperation between the Holy See and Washington in the containment of Communism and the work of charity and assistance, at the end of World War II several priests and bishops from the United States assumed quite significant roles in papal diplomacy. These included Msgr. Walter S. Carroll in the Vatican Secretariat of State (1940-1950), Msgr. Aloisius Joseph Muench in Germany (1946-1959), Msgr. Joseph Patrick Hurley in Yugoslavia (1945-1950) and Rev. Edward J. Killion in Geneva (1947-1953). This book examines the activity of these actors during the years of Pius XII’s pontificate. The contributors include historians who have previously addressed the general aspects of the Holy See’s diplomatic strategy, as well as archivists familiar with Vatican documents relating to Pius XII’s pontificate.