This article offers a theoretical explanation of the transformation of national identity in the Republic of Ireland. Because of fundamental changes in the nature of Irish society, the post‐colonial nationalism of the de Valera era has given way to a much more cosmopolitan sense of self. Initially after independence, Irish nationalists strove to recreate an authentic Gaelic world as they idealized it. Ultimately, this conception of Irish national identity was challenged by the forces of urbanization, industrialization, secularization, and more cosmopolitan values emanating from the rest of Europe. Census and survey data provide empirical evidence that changes in the social bases of Irish nationalist identity has indeed transformed a historic ethno‐nationalism into a more secular and potentially less divisive basis of political identificat