In her own time, Margaret McNair Stokes (1832-1900) was an esteemed antiquarian and artist. Her work on early Christian architecture and monumental sculpture in Ireland was pioneering and foundational and continues to inform contemporary research on these topics. Facilitated by her family and their social networks, Stokes was part of an active antiquarian culture based in Dublin which involved membership of scholarly associations as well as social events both at home and on tour throughout the country. Stokes played an important role within these circles, taking on significant editorial projects as well as advancing her own research interests. However, in order to critically assess Stokes's specific contribution to Irish antiquarianism, this article examines two key aspects of her work - the development of new methodologies for the study of Irish sculptured stone monuments, and her advancement of a specific model of periodisation in relation to Irish medieval art and architecture, one which was highly nationalistic, focused on ideas of cultural purity, and which eschewed the prevailing trends within Irish antiquarianism and historiography away from politicised interpretations of the Irish early Christian and medieval past. In considering these facets of Stokes's contribution to Irish antiquarianism and historiography, this article repositions her as a pivotal figure, forging and heralding significant changes of scholarly direction in relation to the fields of research in which she engaged.