Offering a kaleidoscopic perspective on the experiences of Italian workers on foreign soil, Italian Workers of the World explores the complex links between international class formation and nation building. Distinguished by an international panel of contributors, this wide-ranging volume examines how the reception of immigrants in their new countries shaped their sense of national identity and helped determine the nature of the multiethnic states in which they settled. In Argentina and Brazil, Italian migrants were welcomed as a civilizing influence and were instrumental in establishing and leading syndicalist and anarcho-syndicalist labor movements committed to labor internationalism. In the United States, by contrast, where Italian workers were greeted by the American Federation of Labor's hostility to socialism, internationalism, and unskilled laborers, they organized in ethnically mixed unions, including the radical Industrial Workers of the World. The xenophobia they encountered in the "land of opportunity" ultimately encouraged sympathy among Italian Americans for Mussolini's modernizing, imperialist ambitions for the Italian state. Covering the work of republican "Garibaldians" in South America and antifascist currents among Italian migrants in France and the United States, as well as such seminal events as the 1912 textile strike in Lawrence, Massachusetts, and Mussolini's invasion of Ethiopia, Italian Workers of the World shows how modes of incorporating (or excluding) foreign-born workers were carried over from nineteenth-century labor movements to twentieth-century nation-states. This volume also paves the way for new modes of collaboration across the boundaries of historical nationalism.