Recent research consistently reports that persistent poverty has more detrimental effects on IQ, school achievement, and socioemotional functioning than transitory poverty, with children experiencing both types of poverty generally doing less well than never-poor children. Higher rates of perinatal complications, reduced access to resources that buffer the negative effects of perinatal complications, increased exposure to lead, and less home-based cognitive stimulation partly account for diminished cognitive functioning in poor children. These factors, along with lower teacher expectancies and poorer academic-readiness skills, also appear to contribute to lower levels of school achievement among poor children. The link between socioeconomic disadvantage and children's socioemotional functioning appears to be mediated partly by harsh, inconsistent parenting and elevated exposure to acute and chronic stressors. The implications of research findings for practice and policy are considered.