The increase in Italian American political power from the 1920s through the 1940s coincided with the rise of Fascism in Italy and Americanism in the United States—two opposing ideologies that greatly influenced how Italians practiced political citizenship. Benito Mussolini’s Fascist ideology demanded Italians’ permanent subservience to the Italian corporate state, even to the seventh generation abroad. At the same time, American xenophobes pushed an aggressive platform of Americanism; an anti-immigrant ideology that demanded foreigners’ total loyalty to America, its Constitution, and its Anglo-Saxon culture. Scholars have separately noted Italian Americans’ overwhelming support of Fascism and the dramatic rise in their electoral participation during the Great Depression, but few have investigated the overlap between those two developments. None have placed Italian Americans’ growing ethnic awareness within the context of Americanism. This dissertation uncovers the causal relationship between Italian Americans’ Fascism and their newfound political capital, and demonstrates how ethnic elites pushed politicians from adhering to strict Americanism to accepting ethnic political citizenship and transnational activism. Beginning in 1930, Italian American elites made shrewd choices about how Fascism would spread and function in the United States to avoid government investigations. Italian immigrants first organized pro-Fascist clubs to find a collective purpose as transnationalistic citizens. Hoping to prove their value to Italy, immigrant elites first used their clubs to mobilize their growing communities in support of favorable terms of repayment for Italy’s World War I debt to the United States. The war debt campaign taught the Italian government and pro-Fascist immigrants that Italian Americans had potential for great political power, but only if they naturalized. To pursue naturalization and ethnic politics simultaneously they first needed to overcome their ideological conflicts with the Americanist values of total assimilation. Italian American elites resolved the tensions of choosing between Americanism and Fascism by bringing their communities together around an ethno-cultural nationalism, called Italianità, that pursued the ascension of Italian Americans in the United States and the supremacy of Italy in Europe. Italianità allowed immigrants to exercise transnational citizenship by using culture as a screen for advancing their political causes, helping them avoid criticism. Seemingly apolitical events organized by Mussolini’s supporters, like Columbus Day rallies, brought Italian Americans masses to the attention of American politicians at a crucial moment in electoral campaigns. The more active Italian Americans became in support of themselves and their homeland, the more aggressively American politicians courted their votes. By 1941, Italians had far surpassed Germans and Japanese in continual demonstrations of pro-Fascist nationalism through Italianità. Because they also eclipsed their co-ethnics in American voting power, the government largely ignored Italians in its extensive investigations of un-American activities before and after Pearl Harbor. This dissertation is the first to recognize the political roots of the government’s investigations into Germans and Italians and the resulting arrests during the war. The strategies employed by immigrant elites in the 1920s and 1930s enabled Italian ethnics to escape the mass internment and arrests of the 1940s. Rather than shrink from their ethnic identity, Italian Americans employed the full weight of their political capital to serve their community through the end of World War II.