The United States invests far more in providing clinical services than in addressing social and behavioral factors that powerfully affect health and mortality compared with other high-income nations that have better health.1 The United States has also large avoidable differences in health across groups, eg, life expectancy of 40-year-old men in the poorest 1% of the income distribution is 14.6 years shorter than for men in the richest 1%, and for women, the difference is 10.1 years.2 Health disparities are found also by education, race, ethnicity, sex, sexual orientation, and place of residence. Policies that reduce social disadvantage can reduce health inequalities, for example, the health gap between blacks and whites narrowed in the decades after civil rights legislation. The comparatively poor health status of the US population, existence of health inequalities, and fluctuations in health in relation to policy-driven changes in social conditions highlight the importance of policies addressing social determinants. Socioeconomic conditions underlie many health inequalities and compel attention to social policies that affect health, strengthening existing programs that can reduce disparities, and shifting health financing to reward improvements in individual and community health.