Married couples in Córdoba City (Argentina) were studied from the census data of 1778, 1795, 1813, 1822, and 1832. Homogamy regarding ethnic group, juridical status, and the title “Don/Doña” was analyzed through contingence coefficients as well as inbreeding and mate preferences among lineages, using the isonymy and repeated pair methods. Class endogamy was revealed in all groups and homogamy was found for various characteristics. The inbreeding was low, but repeated pairs of surnames indicated associated family lines in the Spanish group. A temporal analysis showed that both indicators were higher in times of sociopolitical instability.