This article seeks to define and characterize the urban structure of Santiago, Chile, based on the relation between its inhabitants’ places of residency and work, which form local labour market zones. The article explains the criteria and methodological procedures used to define these zones, and it describes them on the basis of this functional definition, to determine the extent to which they underpin the social inequalities prevailing in the city. It also makes a spatial analysis of income inequality, access to education and the composition of the social classes.