We present the results of a meta-analytic review of early developmental prevention programs (children aged 0-5: structured preschool programs, center-based developmental day care, home visitation, family support services and parental education) delivered to at-risk populations on non-health outcomes during adolescence (educational success, cognitive development, social-emotional development, deviance, social participation, involvement in criminal justice, and family well-being). This review improves on previous meta-analyses because it includes a more comprehensive set of adolescent outcomes, it focuses on measures that are psychometrically valid, and it includes a more detailed analysis of program moderator effects. Seventeen studies, based on eleven interventions (all US-based) met the ten criteria for inclusion into the analysis. The mean effect size across all programs and outcomes was 0.313, equivalent to a 62% higher mean score for an intervention group than for a control group. The largest effect was for educational success during adolescence (effect size 0.53) followed by social deviance (0.48), social participation (0.37), cognitive development (0.34), involvement in criminal justice (0.24), family well-being (0.18), and social-emotional development (0.16). Programs that lasted longer than three years were associated with larger sample means than programs that were longer than one year but shorter than three years. More intense programs (those with more than 500 sessions per participant) also had larger means than less intense programs. There was a marginally significant trend for programs with a follow-through component into the early primary school years (e.g. preschool to Grade 3) to have more positive effects than programs without a follow-through. We conclude that the impact of well-conducted early development programs on quality of life in adolescence can be substantial for social policy purposes.