We introduce a new approach to behaviour change called 'Evo-Eco' because of its intellectual roots in evolutionary biology and ecological psychology. This approach is based on the inference that behaviour evolved as a system designed through evolutionary history to provide adaptive responses to rapidly changing or complex environmental conditions. A need for behaviour change should therefore arise when individuals fail to learn appropriately from experience, due to some mismatch between environmental stimuli and learning mechanisms, leading to inappropriate behaviour. The approach therefore begins from a well-established model of how agents typically learn from experience of particular environmental circumstancesthe reinforcement learning model. This basic model is then expanded to determine in greater detail what kinds of learning failures can occur. Consideration of findings from the sciences relevant to components of the learning model -ranging from evolutionary biology, to ecology and psychology -leads to the development of this new model of behaviour change, which also serves as a theoretically justified checklist of factors for practitioners to examine during program development. We also report that the approach has been used to develop effective public health programs involving behaviour change, as well as to novel predictions about behavioural causes (i.e., placement within a routine) which have proved to impact on the ability to change a behaviour. We therefore hope that the Evo-Eco approach will be used by public health workers and, more generally, by (social) marketers to devise more effective campaigns, by policy-makers to improve general well-being, and by the general public as inspiration for their own self-help projects.