Since the 1970s, scholarship within critical urban studies and its cognate fields has regularly argued that the built environment is central to the reproduction of capitalist society. It has emphasized that due to the dynamism of market-driven competition—and the productivity-enhancing pressures it places upon waged work—capitalist societies perpetually render their built environments obsolete, leading to revolutions in socio-spatial relations. There is much to recommend in this account. It usefully demonstrates that the built environment stands as the presupposition and result of profitable waged exploitation. And yet, in this project, “The Capitalist Spatial Matrix: A Political Theory of the Built Environment,” William Conroy sets out to recast that received theorization. Through an archival reconstruction of key episodes in the history of American heterodox political economic thought, he identifies the unwaged forms of work that undergird capitalist profitability, and he demonstrates how and why the built environment is central to their reproduction—not simply to waged work. Conroy traces debates and struggles surrounding the persistence of unwaged work in American capitalism, from the “black belt debate” of the 1920s and 1930s, which took place within the Communist Party of the United States of America (CPUSA) and considered the persistence of racialized expropriation after the failures of Reconstruction in the US South; to the “domestic labor debate” of the 1970s and 1980s, which grappled with the shifting geographies of women’s reproductive work after the second World War; and beyond. And what he finds embedded in this history are the lineaments for a novel theorization of the role of the built environment in the reproduction of capitalist society and its unwaged conditions of possibility. Indeed, what he finds is that the socio-spatial imaginaries at the core of these debates demonstrate that revolutions in socio-spatial relations are driven not only by productivity-enhancing innovations in the “formal economy” of waged work. They are also driven by capital’s tendency to exhaust its unwaged and non-commodified social and ecological conditions of possibility. In so doing, he provides an archival and intellectual-historical grounding for the claim that the built environment is integral to the reproduction of capitalism not as an economic system, but as an institutionalized social order.