Administrative structure can shape bureaucratic process, performance, and responsiveness and is a particularly important consideration when new bureaucratic functions and programs are being established. However, the factors that influence the assignment of these functions to specific government agencies or departments are understudied, particularly at the local level. The absence of empirical evidence regarding bureaucratic assignment in local government limits understanding of institutional design and the organizational choices available, particularly as they relate to specific policy areas. As an initial step in developing a theory of agency assignment at the local level, we examine the placement of sustainability programs in 401 US cities and assess explanations for assignment based on policy scope, interest group support, governmental capacity, policy characteristics, and institutional structures that shape the incentives of local decision makers. Although it is not a traditional function of local government, sustainability is becoming an increasingly common objective. Because of its newness and cross-cutting nature, local policy makers have an array of institutional units to which they can assign the primary responsibility for sustainability. We focus on two dimensions of assignment of bureaucratic responsibility: whether the locus of responsibility lies within the executive or a line department and whether there is a specialized unit within the city government that is explicitly responsible for sustainability. The scope and maturity of cities’ sustainability policies and the structure of local representation (i.e., whether council representatives are elected by district, at-large, or via a mixed system) have the greatest influence on shaping administrative placement. The latter suggests potential distributive outcomes from local sustainability efforts.