This article presents a new measure of family-driven age- and gender-related inequalities. This composite measure, which we call the Patriarchy Index, combines a range of variables related to familial behavior that reflect varying degrees of sex- and age-related social inequality across different family settings. We demonstrate the comparative advantages of the index by showing how 266 historical populations from the Atlantic coast of Europe to Moscow scored on the patriarchy scale. We then compare the index with contemporary measures of gender discrimination, and find a strong correlation between historical and current inequality patterns. Finally, we explore how variation in patriarchy levels across Europe is related to the socioeconomic and institutional characteristics of the regional populations, and to variation across these regions in their degree of demographic centrality and environmental conditions. The results confirm previous findings that family organization is a crucial generator of social inequality, and point to the importance of considering the historical context when analyzing the current global contours of inequality.