The theory of proto-industrialization holds that a major expansion of rural industry, primarily in textiles, formed a phase precursory to industrialization in many European regions. This phase was characterized by sweeping economic and demographic changes, including increasing population density, land subdivision, and agricultural intensification. Domestic industry boosted marriage rates and may have lowered the average age of marriage of rural dwellers. The present research examines the tenets of this theory for the case of Ireland, a country affected by rural industrialization in the eighteenth and early nineteenth centuries. The data are cross-sectional and are drawn primarily from the 1841 census.