Most of the literature concerning the momentous challenges facing Irish American Catholics in the first two decades of the twentieth century pay but scant attention to the role played in addressing them by the American Church. Among the myriad political, social, cultural and economic issues confronting Irish American Catholics none stand out as prominently as the unabated burden of combatting scurrilous attacks upon them by na-tivist forces, the task of proving themselves as loyal American citizens, and navigating the perilous waves in advancing the course of directing Irish American nationalism and the cause of Ireland's freedom. Patriotism is a Catholic Virtue ferrets out the impact the institutional Church played in affecting the course of action Irish American Catholics took regarding these three crucial missions. Whereas the task of con-fronting the assaults of nativism, seemingly the natural task for the insti-tutional Church, this study provides extensive evidence of the relentless defense of Catholic virtue conducted by diocesan newspapers. Similarly, the mission of promoting Catholics as loyal American citizens was largely left in the hands of the American hierarchy, its clergy, newspapers and Catholic societies and affiliates. Lastly, this book provides evidence that the Church may well have played the decisive role in guiding its Irish American faithful along paths that, while conservatively promoting Irish nationalism, did not jeopardize an "American First" policy for Catholics. All of this was accomplished in the crucible of an emerging worldwide war.