Here are 2 truisms. Rich countries have better health than poor countries, and medical care improves health. Consider, then, the case of the United States, which is among the richest countries in the world and spends more than any other country on medical care, US $6350 per person in 2005.1 Does the United States then have the best health? Not quite. Life expectancy from birth to age 65 years is one useful measure of premature mortality: the United States ranks 36th in the world for men and 42nd for women.2 If not by greater national income or more spending on medical care, how should the task of improving health in the United States be approached? Pay attention to the social determinants of health.