Through the lens of nineteenth-century Irish society and through an interrogation of the diaries of one of the first women professors appointed to the National University of Ireland, this article traces the entry of women into the professoriate in Ireland. The aim of the paper is to extend the map of the international research agenda which speaks to a historiographical deficit in the area of women and the professoriate, interrogating the complex role that the early women professors played in a male hegemonic world. Specifically, the article examines the role and legacy of Professor Mary Hayden (1862-1942), historian and women's rights activist.