Uncorrected vision may present a significant barrier to educational mobility in poor communities in low and middle income countries. Focusing on the case of rural Northwest China, we analyze the Gansu Survey of Children and Families (2,000 children; 100 rural villages) and the Gansu Vision Intervention Project (a randomized trial; 19,185 students, 165 schools, two counties). Four main findings emerge: significant unmet need for vision correction; socioeconomic gradients in vision correction; somewhat greater vulnerability to vision problems among higher socioeconomic status and more academically engaged children; and significant favorable effects of vision correction on math and literacy performance and class failure.