The anthropological study of the city's role in the evolution of human systems requires the use of both macro and micro levels of analysis. From the macro perspective, the city is viewed as part of a wider complex society, while from the micro point of view, the city provides the context for understanding specific human institutions or processes within the urban area. The necessary link between the two levels of analysis is provided by research on another level, one that focuses on the city itself and its internal complexity. A study of urban households in Oaxaca City, Mexico, demonstrates how research that uses the city as the unit of analysis may be conducted. The first phase of the research involved the data collection of the physical and social environment in order to provide a general description and the basis for developing a typology of residence patterns in the city. The second phase involved the collection of socioeconomic data for the different types of localities indentified in the first phase. The study showed that in conducting anthropological research on the city, the unit of analysis should be easily identifiable as well as representative, and that studies in such complex urban settings should be undertaken by groups rather than by single individuals. (MJL)