What are the characteristics of programs that have the greatest likelihood of success in promoting the development of very young children at risk? This brief review of research offers insights for policy makers and early childhood educators alike. The United States is fortunate to have well-designed early educational intervention programs that may buffer the effects of poverty and facilitate healthy development of children. The impact studies on those programs show that several conditions are necessary for early intervention to be successful: (1) When interventions begin before children reach school age, and are intensive and direct, children who are at risk may demonstrate better cognitive, behavior, and socioemotional outcomes than those who receive intervention after preschool; (2) Programs that enroll children during infancy and provide education for their families produce greater benefits; (3) Programs that are intensive and multi-generational are thought to produce better outcomes; and (4) Intensive full-day programs produce better developmental outcomes for children at risk. The Abecedarian Project and the Perry Preschool Program are excellent examples of early intervention programs for children at risk, especially with regard to infants and toddlers as well as preschoolers. These intervention programs had short- and long-term effects on the cognitive and socioemotional development of children.