The past century has seen vast improvements in our children's health. The infectious diseases that once killed huge numbers of children have largely been conquered. Infant mortality has also fallen markedly, although the United States lags behind other industrialized nations in this and other measures of children's health. Accidents and injuries also kill fewer children than they once did. Today, write Sara Rosenbaum and Robert Blum, the greatest threats to U.S. children's health are social and environmental conditions, such as stress and exposure to toxic substances, which are associated with noncommunicable illnesses, such as mental health problems and asthma. Unlike the communicable diseases of the past, these are not equal-opportunity hazards. They are far more likely to affect poor children and the children of racial and ethnic minorities. And they have long-lasting effects, both for individuals and for the nation. For example, people who experience unhealthy levels of stress as children grow up to become less healthy, less productive adults. Rosenbaum and Blum also examine government spending on children's health. Though such spending has increased over time, the largest share of that increased spending has been for health care, while spending on other determinants of child health, which may be as or more important, has not kept pace. Investments in medical care alone can't overcome social and environmental threats to children's health that have their roots in historic levels of poverty and inequality. Rosenbaum and Blum argue that the best way to promote children's health today is to mitigate poverty, invest in education, and make our neighborhoods and communities healthier and safer.