The aim of this study is to investigate the differences in and similarities between Protestant and Catholic antiquarian cultures in Ireland in the period 1830 to 1876. The thesis demonstrates that there were notable differences, which were largely due to matters of religion. It focuses upon a select group of scholars (John O’Donovan, Eugene O’Curry, James Henthorn Todd, William Wilde, George Petrie, Denis Henry Kelly, William Reeves, John Windele, Owen Connellan, James Hardiman, and Robert Shipboy MacAdam) from both religious confessions, who were the most prolific antiquarians of this time, and it examines their works and the contexts in which they were written. Using a new historicist methodology, this thesis highlights trends in antiquarian research, its dissemination, and modes of working and ascribes them to a particular religious community.This work is organised in three separate parts. In part one, a brief overview of the development of Irish antiquarianism from the early seventeenth to the late eighteenth century is presented in order to illustrate long-standing sectarian differences and their impact upon antiquarian pursuits in the nineteenth century.Previous scholarship has traditionally categorised the antiquarians studied in this thesis according to ethnicity (Gaelic Irish versus Anglo-Irish). Conversely, part two demonstrates that religion, and not ethnicity, was the greatest dividing social factor in Irish antiquarian circles in the first half of the nineteenth-century. Furthermore, it is demonstrated that emphasis on ethnicity and race only emerged after works had been published relating to that topic from the 1850s. Thus, part two is a comparative study between Protestant and Catholic antiquarian cultures in the nineteenth century, focusing particularly on the differences between the two in terms of subject matter and methodology employed.Part three traces the influence of antiquarian works on Cultural Nationalist ideology and thought at the end of the nineteenth century and in the first decades of the twentieth. In focusing specifically on the influence of antiquarian works on the images of ‘Irishness’ advanced by the Cultural Nationalists during this period, I determine that it was in fact Catholic antiquarian works that had a greater impact on the Cultural Nationalist discourse.