In 2006, Massachusetts passed health care reform legislation designed to achieve nearly universal coverage through a combination of insurance market reforms, mandates, and subsidies that later served as the model for national reform. Using data from the Behavioral Risk Factor Surveillance System, we provide evidence that health care reform in Massachusetts led to better overall self-assessed health. Various robustness checks and placebo tests support a causal interpretation of the results. We also document improvements in several determinants of overall health: physical health, mental health, functional limitations, joint disorders, and body mass index. Next, we show that the effects on overall health were strongest among those with low incomes, nonwhites, near-elderly adults, and women. Finally, we use the reform to instrument for health insurance and estimate a sizeable impact of coverage on health.