This chapter reviews differences with respect to health outcomes within and between countries, and the role of family, household, community and societal conditions, or the ‘social determinants of health’ (SDH) in shaping these outcomes. The pathways from before birth, through the early childhood years, to adolescence and adult health are explored, in particular looking at relationships between health and wealth, as manifested through a range of social, economic and political factors. The fact that national wealth is more reliably associated with better child health where adequate resources are channelled into public and social goods – clean water and sanitation, education, basic health care, social protection – is emphasised. National, and increasingly global, influences on countries’ ability to raise domestic revenue and finance public services are considered, including aid, trade and the international and multilateral systems. While social determinants of health account for a very substantial proportion of child health outcomes in countries at all levels of economic development, there is a trend for research influencing policy to give priority to biological and behavioural choices. In a rapidly globalising world, more effort is required to elucidate the channels between global, national and local actors in the generation and equitable distribution of resources as they determine health.