Abstract: This dissertation is a political economic examination of access to food, food supply policies and well-being in late colonial Mexico, a period of strong transformations in economic organization, distribution of resources and political power. The study begins with an analysis of heights, an indicator of nutritional status and biological well-being. Height declined significantly in the mid eighteenth century, and afterward it stagnated through the early national era. More significantly, socioeconomic height gaps broadened, while the urban-rural height differential decreased (and even changed direction in favor of city dwellers), suggesting important redistributions of resources and particularly access to food in the late colonial and early national periods. Since the market was a major means to acquire food, chapters 2 and 3 focus on grain markets in the late colonial period. I find that grain markets were more competitive than usually assumed and were becoming more integrated in the last decades of the colonial period. I argue that the pronounced food shortages of the late colonial period were not the consequence of the fragmentation of markets and the manipulation of a local oligarchy, but of the decline of market entitlements due to increasing impoverishment and rising inequality. Market integration was beneficial to the cities because they had greater economic and institutional resources (such as purchasing power, a reserve granary, tithe stocks or Church-sponsored charity) to secure the access to food. The political significance of grain markets is finally apparent in the policies and conflicts about trade between jurisdictions and in the discourse on abuses in grain markets, examined in chapters 4 and 5. The priority of the colonial authorities was to secure access to food to the cities, mining centers, and (in the 1810s) the army, the small fraction of the population on which the regime was more crucially dependent.