Anthropologists and geographers have long challenged reified theories of the state as a coherent whole representing strategic interests and promoting unified political projects. Instead the power of the state has been identified in its ability to sustain its own myth through negotiating its relation to civil society, through peopled practices, and through the spatialization of authority. This paper develops an ethnographic account of the recent enthusiasm for Behaviour Change in UK public policy, the consequences of which are two-fold. First we demonstrate how an anthropological perspective explains the emergence of Behaviour Change as a set of ideas, people, organisations, events and happenings: not only as a sometimes contradictory policy ‘agenda’, but as a diverse and novel industry or cadre of expertise; and one that is played out in geographical ways. Secondly, we seek to show how the particularities of Behaviour Change policies pose new challenges to anthropological approaches to the state.