My dissertation offers a revaluation of the intellectual and historical origins that inform the works of literary modernism. Drawing on the work many of the authors of the modernist period and on recent modernist scholarship, it argues for the necessity of understanding modernism as a philosophical and artistic formation that represents and resists the variety of perceived crises and historical ruptures that constitute modernity. Within this framework of 'modernism against modernity,' it suggests that Catholic intellectual and political developments played a significant role in providing modernist figures a model for resistance to modernity. The dissertation focuses on three Irish modernist poets – Brian Coffey, Denis Devlin, and Thomas MacGreevy. All three were well situated within the milieus of Anglophone modernism, French surrealism, the Thomistic-revival, and Irish nationalism. Their poetry and criticism provide case studies for the way in which Irish writers attempted to work through their postcolonial legacy in terms of Church/State relations. Resistant to Irish Protestant liberalism and nationalist ruralism alike, they embraced continental philosophy, avant-garde experimentation and, above all, international modernist aesthetics as means of moving Irish writing beyond provincial sectarianism and stifling romantic images of the nation. In contrast to most writers of the period, they saw Catholicism not as a sign of Irish provincialism but, as the Universal Church, the natural tradition and theological framework in which to work out the troubles of Irishness and the modern condition in general. Each of the writers developed the innovations of poetic modernism in order to bring out its incipiently Catholic elements. The results were a variety of critical and poetic works simultaneously representative of modernist practices in general (particularly in the development of denaturalized, deracinated literary language and forms that absorbed but spoke above locale dialects), and yet shaped by Catholic cultural traditions and, more than that, the developments of Catholic theological modernism and neo-Thomist philosophy and theology. Each writer found ways to harness the ironic, ontological and mystical languages of literary modernism for explicitly Catholic ends, but the novelty of their efforts emerges most clearly in their success at making modernism itself appear as an adjunct of Catholicism.