School-based programmes developed to promote social and emotional well-being aims to reduce the risk of academic failure and other negative outcomes, such as antisocial behaviour and mental health problems. This article maps the British political trajectory from understanding the importance of social and emotional well-being, to delivering programmes in schools that enhance it. It summarises the outcomes of a selective review of effective school-based interventions and draws out lessons for policy and practice regarding choice and implementation of programmes. Amongst universal and targeted evidence-based interventions, multi-modal/component approaches appear useful in promoting cross-context competence and well-being. However, the scaling up of effective programmes remains unsuccessful and there is a lack of cost-effectiveness or cost-benefit analyses surrounding effective programmes. Despite these drawbacks there is a greater understanding of what constitutes "evidence" and how it can facilitate policy-makers' selection process when identifying a promising or effective programmes. There is a need to address ongoing outcome and process evaluation, and delivery and resource factors in order to ensure fidelity in programme implementation, and replication of positive outcomes. (Contains 2 tables.)