Across the post-industrial world, new public health strategies are being developed with the goal of reducing the socio-economic gradient in health. These new strategies are distinguished by a commitment to tackling the macro determinants of health inequalities through policies informed by scientific evidence. The engagement with macro determinants and with scientific evidence presents a major challenge to the health inequality research community. This is not only because of the complexity of the links between distal causes, proximal risk factors and health outcomes. It is also and more importantly because of the narrow disciplinary base of health inequality research. Grounded in social epidemiology, health inequality research has illuminated the pathways which run from individual socio-economic position to health-but has left in shadow the factors which influence socio-economic position. Broadening the evidence base to include these structural processes requires a new science of health inequalities, resourced both by epidemiological research and by research on social inequality and social exclusion. The paper demonstrates how such an inter-disciplinary science can be constructed. Taking lifecourse research as its example and the UK as its case study, it nests epidemiological research within social policy research: setting evidence on the health consequences of cumulative exposures within research on lifecourse dynamics, and locating both within analyses of how state policies can amplify or moderate inequalities in socio-economic position.