This article reviews empirical evidence on the micro-level consequences of family planning programs in middle- and low-income countries. In doing so, it focuses on fertility outcomes (the number and timing of births), women’s health and socioeconomic outcomes (mortality, human capital, and labor force participation), and children’s health and socio-economic outcomes throughout the life cycle. Among the studies we reviewed, program effects ranged between 5 and 35 percent fewer children ever born and 5–7 percent longer births intervals. Relative to background fertility decline, however, real-world family planning programs explain only a modest share (about 4–20 percent of the total fertility decline among studies reporting significant effects). Family planning programs may also have quantitatively modest—but practically meaningful—effects on the socio-economic welfare of individuals and families.