It appears that recent debates within human geography, and the broader social sciences, concerning the more-than-rational constitution of human decision-making are now being paralleled by changes in the ways in which public policy makers are conceiving of and addressing human behaviour. This paper focuses on the rise of so-called Behaviour Change policies in public policy in the UK. Behaviour Change policies draw on the behavioural insights being developed within the neurosciences, behavioural economics and psychology. These new behavioural theories suggest not only that human decision-making relies on a previously overlooked irrational component, but that the irrationality of decision-making is sufficiently consistent to enable effective public policy intervention into the varied times and spaces that surround human decisions. This paper charts the emergence of Behaviour Change policies within a range of British public policy sectors, and the political and scientific antecedents of such policies. Ultimately, the paper develops a geographically informed, ethical critique of the contemporary Behaviour Change regime that is emerging in the UK. Drawing on thirty in-depth interviews with leading policy executives, and case studies that reflect the application of Behaviour Change policies on the design and constitution of British streets, the analysis claims that current strategies are predicated on a partial reading of new behavioural theories. We argue that this partial reading of human cognition is leading to the construction of public policies that seek to arbitrarily decouple the rational and emotional components of human decision-making with deleterious social and political consequences.