This article explores the potential to mobilize in an urban context the key insights of the burgeoning literature on the performativity of economics. It argues that our understanding of contemporary urban political-economic transformation needs to explicitly recognize the active role of economics in making and remaking the urban world, as opposed to merely describing and analysing it in some kind of passive, detached fashion. It develops this argument through the elaboration of a case study of just such world-making in action: the growing use in the United Kingdom, since the early 2000s, of economic models for assessing the viability of affordable housing provision in new residential developments. The world of urban redevelopment that such models attempt to describe formulaically has, the article submits, increasingly come to act according to the model and the assumptions it contains; the model, in this sense, has been progressively actualized in the urban landscape. The article conceptualizes such performative economic models as examples of what Michel Callon calls economics ‘in the wild’, and it focuses on the work of the leading commercial developer and marketer of such models in the affordable housing planning environment over the last decade — a consulting company called Three Dragons.