This paper examines the impact on student learning of the Programa para Abatir el Rezago Educativo (PARE), which aimed to improve the quality and efficiency of primary education in four Mexican states by increasing school resources. PARE was implemented in the states of Oaxaca, Guerrero, Chiapas, and Hidalgo, which have the highest incidence of poverty and the lowest education indicators in Mexico. The most disadvantaged schools in these states are those serving rural and Native (non-Spanish-speaking) students. Control data were collected from comparable schools in the state of Michoacan, which did not implement PARE. PARE provided participant schools with additional resources such as libraries, textbooks, academic materials, teacher and principal training, and school construction and repair. Analysis focused on (non-Native) rural and Native schools, where student achievement was typically low. Measured by students' achievement test scores in Spanish in grades 4 and 6, student performance in PARE schools improved significantly in both the rural and Native subsamples. PARE also increased the likelihood that a student would continue in school, but only for the rural subsample. The findings suggest that doubling the resources allocated per student could overcome a 30 percent deficit in test scores among rural students. (Contains 14 data tables and a list of definitions of variables.) (SV)