This dissertation research examines neighborhood socio-spatial organization at Calixtlahuaca, a Postclassic (1100-1520 AD) urban center in highland Mesoamerica. Neighborhoods are small spatial units where residents interact at a face to face level in the process of daily activities. How were Calixtlahuaca's neighborhoods organized socio-spatially? Were they homogenous or did each neighborhood contain a mixture of different social and economic groups? Calixtlahuaca was a large Aztec-period city-state located in the frontier region between the Tarascan and Triple Alliance empires. As the capital of the Maltazinco polity, administrative, ritual, and economic activities were located here. Four languages, Matlazinca, Mazahua, Otomi, and Nahua, were spoken by the city's inhabitants. The combination of political geography and an unusual urban center provides an opportunity for examining complex neighborhood socio-spatial organization in a Mesoamerican setting. The evidence presented in this dissertation shows that Calixtlahuaca's neighborhoods were socially heterogeneous spaces were residents from multiple social groups and classes coexisted. This further suggests that the cross-cutting ties between neighborhood residents had more impact on influencing certain economic choices than close proximity in residential location. Market areas were the one way that the city was clearly divided spatially into two regions but consumer preferences within the confines of economic resources were similar in both regions. This research employs artifact collections recovered during the Calixtlahuaca Archaeological Project surface survey. The consumption practices of the residents of Calixtlahuaca are used to define membership into several social groups in order to determine the socio-spatial pattern of the city. Economic aspects of city life are examined through the identification of separate market areas that relate to neighborhood patterns. Excavation data was also examined as an alternate line of evidence for each case. The project contributes to the sparse literature on preindustrial urban neighborhoods. Research into social segregation or social clustering in modern cities is plentiful, but few studies examine the patterns of social clustering in the past. Most research in Mesoamerica focuses on the clustering of social class.