This dissertation analyzes the urban planning and political brokering that transformed Mexico City into one of the largest cities in the world in the twentieth century. It focuses on Mexico City’s colonias proletarias, the peripheral settlements of the city that are commonly understood as anarchic and “informal” spaces. Pushing against narratives that posit Mexico City’s disorderly growth, I describe how municipal planners, political brokers, and resident associations, while following their own conflicting interests and urban visions, shaped Mexico City’s colonias proletarias between 1930 and 1960. The outcome of this partnership was not an ideal city but the regulation of access to, and rights over, housing, land, and urban services. This planning mode was neither democratic nor technically rational but it channeled collective action, prevented violent conflict amidst dramatic change, and successfully combined stability with urban growth. Through the use of unexplored municipal archives that cover both comprehensive city projects and local conflicts over urban space, I offer an original approach to urban planning that integrates expert planning visions with descriptions of how Mexico City’s urban periphery was settled and built. Rather than centering on the failures and successes of notorious urban planners, I provide a decentralized and local analysis of city management and politics, describing how land was subdivided, allocated among urban residents, and provisioned with urban services. Undertaking these actions implied, in practice, distributing duties among government and non-government actors and defining the proper scale (e.g., neighborhood, district, and citywide) at which they intervened in the city.