This article presents new evidence and analysis on age heaping—a proxy for numeracy and therefore for human capital—in New Spain during the Enlightenment. Human capital plays an important role in economic growth and welfare. It is also one of the dimensions of inequality. Our results are at odds with many of the usual assumptions on which most Mexicanist historiography is based. Age heaping levels of males and females and ethnic groups across locations in Central New Spain are estimated and compared through ad hoc indicators with other countries. We infer that a more empirical emphasis on the institutional legacy of the viceregal period and more attention to human capital since pre-Conquest times will benefit the progress of Hispanic American economic history.