We investigate the historical determinants of the education gender gap in Italy in the late nineteenth century, immediately following the country's Unification. We use a comprehensive newly-assembled database including 69 provinces over twenty-year sub-samples covering the 1861-1901 period. We find robust evidence that female primary school attainment, relative to that of males, is positively associated with the medieval pattern of commerce, along the routes that connected Italian cities among themselves and with the rest of the world. The effect of medieval commerce is particularly strong at the non-compulsory upper-primary level and persists even after controlling for alternative long-term determinants reflecting the geographic, economic, political, and cultural differentiation of medieval Italy. The long-term influence of medieval commerce quickly dissipates after national compulsory primary schooling is imposed at Unification, suggesting that the channel of transmission was the larger provision of education for girls in commercial centers.