Most poor children achieve less, exhibit more problem behaviors and are less healthy than children reared in more affluent families. We look beyond correlations such as these to a recent set of studies that attempt to assess the causal impact of childhood poverty on adult well-being. We pay particular attention to the potentially harmful effects of poverty early in childhood on adult labor market success (as measured by earnings), but also show results for other outcomes, including out-of-wedlock childbearing, criminal arrests and health status. Evidence suggests that early poverty has substantial detrimental effects on adult earnings and work hours, but on neither general adult health nor such behavioral outcomes as out-of-wedlock childbearing and arrests. We discuss implications for indicators tracking child well-being as well as policies designed to promote the well-being of children.