There are dramatic differences in health between countries and within countries. But this is not a simple matter of rich and poor. A poor man in Glasgow is rich compared to the average Indian, but the Glaswegian's life expectancy is 8 years shorter. The Indian is dying of infectious disease linked to his poverty; the Glaswegian of violent death, suicide, heart disease linked to a rich country's version of disadvantage. What makes these health inequalities unjust is that evidence from round the world shows we know what to do to make them smaller. This new evidence is compelling. It has the potential to change radically the way we think about health, and indeed society.