IN MANY SOCIETIES, BUT ESPECIALLY IN THE UNITED STATES, the reverberations of inequality are felt most profoundly by children growing up in poverty. Poverty increases the risk that they will not be ready for school by age 5, will not complete high school, and will be poor as adults. A lack of high-quality pre-schools, secondary schools that are poorly funded and ineffective, challenging neighborhoods, and limited parental resources, among other variables, contribute to these odds. These factors are compounded, however, by the ways that inequality literally gets under the skin, as the toxic stress produced by poverty affects brain and bodily development in early childhood. Combining the perspectives of neuroscience and sociology, brothers BRUCE MCEWEN, head of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology at The Rockefeller University, and CRAIG MCEWEN, Emeritus Professor of Sociology at Bowdoin College, explore the feedback loops between social inequalities and biological responses to chronic stress, which create potentially life-long consequences for health and life trajectories. As much as neuroscience is key to understanding these effects, the sociological perspective cautions against too narrow a focus on biology. There is the risk of medicalization, which defines problems of adversity primarily as medical conditions requiring individual diagnosis and treatment. Sociological perspectives emphasize the social structures and practices that give rise to adversities and the resources that can protect against their potential impact on bodies and brains. This perspective turns attention to social policies to reduce adversities and to development of community resources to protect against them.