Through a genealogical analysis of the terms mestizo and mestizaje, this article reveals that these voices are doubly hybrid. On the one hand they house an empirical hybridity, built upon eighteenth and nineteenth century racial taxonomies and according to which ‘mestizos’ are non-indigenous individuals, the result of biological or cultural mixtures. Yet, mestizos’ genealogy starts earlier, when ‘mixture’ denoted transgression of the rule of faith, and its statutes of purity. Within this taxonomic regime mestizos could be, at the same time, indigenous. Apparently dominant, racial theories sustained by scientific knowledge mixed with, (rather than cancel) previous faith based racial taxonomies. ‘Mestizo’ thus houses a conceptual hybridity – the mixture of two classificatory regimes – which reveals subordinate alternatives for mestizo subject positions, including forms of indigeneity.