In the quest for sustainable development, numerous examples of ‘best practice’ have been created and circulated in national and international arenas. Yet despite the vast array of examples, demonstration projects, case studies, and the like, little is known about the ways in which best practices are produced and used, and their role in processes of policymaking. Focusing on best practice for urban sustainability, the author argues that, rather than conceptualising its role and impact in terms of policy transfer or lesson drawing, the creation, dissemination, and use of best practice can be better understood as a discursive process, in which not only is new knowledge created about a policy problem, but the nature and interpretation of the policy problem itself are challenged and reframed. Drawing on insights from concepts of governmentality, the author argues that best practices are at once a political rationality and a governmental technology through which the policy problem of urban sustainability is framed and defined. Illustrations of the practice of best practice show how contradictions emerge between claims for general applicability and the need for policy actors to understand the contingencies of the process of urban sustainability, in order to enrol it for their own struggles over sustainability. The local stickiness of best practices points to the very real struggles that the rationalities of urban sustainability have in competing with other governmentalities which seek to shape urban futures.