This dissertation describes the role of architects in the development of the prison system in the United States. In the late eighteenth century, penologists sought to standardize conditions in penal institutions and to develop reliable methods for the social conditioning of inmates. Architects designed prisons that embodied the standards of penal theory, arguing that the form of an institution could serve as a powerful means of assuring that prison routine adhered to the dictates of modern penology. While early prison architects focused upon the development of a standard institutional type, the growth of the penal bureaucracy in the twentieth century forced them to develop a structural vocabulary commensurate with the scale of the modern prison system. They broke the prison down into a series of flexible components, each of which could function effectively in diverse institutional contexts. As criminologists sought to address the ostensible urban crisis in the 1960s, moreover, architects envisioned the extension of the new carceral infrastructure to the city. These techniques served the standardization of the prison system in the twentieth century. Like the early prison architects, modern designers sought to make each element of their structural vocabulary determinative of the activities of inmates and guards in penal institutions. By freeing these elements from the compositional order of early penal institutions, moreover, architects facilitated the rapid expansion of the prison system and the extension of carceral space into new contexts. By the 1970s, the refinement of advanced techniques for the construction of prisons meant that architects no longer played a pivotal role in shaping the prison system. As legal policymakers abandoned rehabilitative penology and emphasized the punitive function of confinement, the techniques of efficient prison construction developed by architects served a massive institutional building campaign whose sole justification was the incapacitation and segregation of the inmate population.