What roles do, can and should cities and their agents play on the international stage? Has the “rescaling” of political authority expanded urban governments' foreign policy space? Can the advocates of urban empowerment exploit cities' growing economic clout to harness urban development? To answer these questions, and to shed light on the international frontiers of metropolitan governance, this study explores the frictions between cities' foreign ambitions and states' collective efforts to preserve their sovereign rights and prerogatives. It proceeds in two parts: to probe the anarchical society's stake in the urban age, the first part maps the transnational activities of cities and their agents. It discusses urban aspirations, surveys foreign engagements and reviews their salience and limitations. To gauge states' collective response to the tentative expansion of metropolitan rule, the second part examines on what terms UN-Habitat, the Cities Alliance and the World Bank harness urban development in poorer and more fragile parts of the world. The study concludes with a critique of the view that international relations are bound to orbit local concerns.