Income is related to health in three ways: through the gross national product of countries, the income of individuals, and the income inequalities among rich nations and among geographic areas. A central question is the degree to which these associations reflect a causal association. If so, redistribution of income would improve health. This paper discusses two ways in which income could be causally related to health: through a direct effect on the material conditions necessary for biological survival, and through an effect on social participation and opportunity to control life circumstances. The fewer goods and services are provided publicly by the community, the more important individual income is for health. Under present U.S. circumstances, a policy of counteracting growing income inequalities through the tax and benefit system and of public provision appears justified.