The Commission on Social Determinants of Health was set up by the World Health Organisation to collate global evidence, raise societal debate and recommend policies, with the goal of improving health and reducing health inequalities between groups.A major thrust of the commission is turning public-health knowledge into political action. There is clear evidence that national policies make a difference, but these policies must not be confined to the healthcare system.How to address the conditions in which people grow, live and work has relevance for law, political science, engineering, biomedicine, anthropology, economics and, indeed, most of the disciplines at UCL.