Emerging research in neuroscience and developmental psychology suggests that poverty early in a child’s life may be particularly harmful because the astonishingly rapid development of young children’s brains leaves them sensitive (and vulnerable) to environmental conditions.After a brief review of possible mechanisms and the highest quality evidence linking poverty to negative childhood outcomes, this paper highlights emerging research linking poverty occurring as early as the prenatal year to adult outcomes as far as the fourth decade of life. Based on this evidence, it discusses how policy might better focus on deep and persistent poverty occurring very early in the childhoods of the poor.