This article draws from ethnographic research on a recently built park in one of Paris' predominately West African and Maghrebi districts. It demonstrates how urban design is used to “build-in” neoliberal subjectivities to the city. This design approach appropriates a tradition of street democracy held by neighborhood associations and redirects their disproportionately middle class, French membership into managerial roles traditionally held by municipal agencies. This neoliberal political subjectivity, which I term vigilant citizenship, makes monitoring and controlling the social composition of the urban commons a form of civic engagement for middle class urbanites. In Paris, this vigilance is fueled by anxieties over the presence of West African and Maghrebi youth in public spaces. Activists do not passively adopt this neoliberal role; they strike a delicate balance as gatekeepers, weighing inclusion against an expectation to maintain a “successful” public space conforming to a republican model of citizenship.