This paper evaluates the impact of Mexico's Progresa program, which provides educational grants to poor mothers in rural areas, on school enrollment. The program was randomly allocated to 495 localities, allowing for a straightforward evaluation of its short-term effects by comparing enrollment rates in treatment and control communities. Pre-program comparisons check the randomized design, and double-difference estimators are used to calculate the program's effect on enrollment by grade and sex. Probit models are also estimated to assess the probability of enrollment, controlling for additional characteristics of the child, their parents, local schools, and community. The short-run effects on enrollment are extrapolated to estimate the long-term impact on lifetime schooling and earnings, providing an assessment of the internal rate of return on public schooling subsidies. The paper discusses alternative social welfare programs, describes the administrative form of Progresa, and presents the conceptual and empirical model of enrollment. It finds that the program significantly increased enrollment rates, particularly among girls, and reduced income-related inequalities in enrollment within localities.This paper evaluates the impact of Mexico's Progresa program, which provides educational grants to poor mothers in rural areas, on school enrollment. The program was randomly allocated to 495 localities, allowing for a straightforward evaluation of its short-term effects by comparing enrollment rates in treatment and control communities. Pre-program comparisons check the randomized design, and double-difference estimators are used to calculate the program's effect on enrollment by grade and sex. Probit models are also estimated to assess the probability of enrollment, controlling for additional characteristics of the child, their parents, local schools, and community. The short-run effects on enrollment are extrapolated to estimate the long-term impact on lifetime schooling and earnings, providing an assessment of the internal rate of return on public schooling subsidies. The paper discusses alternative social welfare programs, describes the administrative form of Progresa, and presents the conceptual and empirical model of enrollment. It finds that the program significantly increased enrollment rates, particularly among girls, and reduced income-related inequalities in enrollment within localities.