We meta-analyze enrollment, attendance and dropout impact and cost-effectiveness estimates from forty-two CCT program evaluations in fifteen developing countries. Average impacts and cost-effectiveness estimates for all outcomes in primary and secondary schooling are statistically different from zero, with considerable heterogeneity. CCT programs are, all else constant, most impactful and cost-effective for programs that, in addition to transfers to families, also provide supply-side complements — such as infrastructure or additional teachers. Impacts are also larger in programs with infrequent payments and more stringent schooling conditions, which aligns with previous single program evidence. Impact and cost-effectiveness estimates from randomized research designs are smaller than those from observational studies.