This article provides a targeted review of the scientific literature on the effects of experienceon early brain and behavioral development and later outcome as it pertains to risk for some formsof child psychopathology. It is argued that ample evidence exists indicating that the prenatal andearly postnatal years likely represent a sensitive period with respect to the effects of stress on thedeveloping nervous system and behavioral outcome, and with respect to the long-term beneficialeffects of early interventions on brain and behavioral development for some genetically baseddisorders, such as phenylketonuria and autism. Moreover, evidence suggests that parental mentalhealth during the first years of life has a significant influence on early brain activity and behavior,and long-term behavioral outcome. It is concluded that, although prevention and earlyintervention efforts should not exclusively focus on the earliest years of development, such effortsshould begin during this period. By directing such efforts toward promoting optimal prenatal andinfant–toddler development, the long-term negative consequences of factors that have theirgreatest influences during early development and which set the stage for future development canbe minimized or avoided entirely. Several recommendations for public policy and future researchpertaining to the effects of early experience on child outcome are offered.