This report reviews the evidence on conditional cash transfers (CCTs) — safety net programs that have become popular in developing countries over the last decade. This report considers the impact that CCTs have had on current poverty, education, health, and nutrition outcomes. It draws heavily on a large number of carefully constructed impact evaluations of CCT programs to conclude that CCTs generally have been successful in reducing poverty and encouraging parents to invest in the health and education of their children, while recognizing that even the best-designed and best-managed program cannot fulfill all of the needs of a comprehensive social protection system.