This study explores the effect of attending school on children's achievement in reading and mathematics and on a test of general information. The major focus was on the interaction between three variables: children's age [young (6-8 years) or old (9-12)], location (city slums or rural villages in the highland or jungle areas of Peru), and the number of years of schooling (none, 1, 2, or 3 years). A follow-up study was conducted nine years after the original testing. Schooling had a positive effect on children's performance, but the degree of influence depended upon all three of the major variables. Schooling tended to have a greater effect on the achievement scores than on the general information scores. In general, scores were highest among children residing in the city and lowest among children living in the remote jungle areas. After controlling for location, age, and years of education, family variables such as parental education and home quality had a small, but significant influence on children's knowledge of reading, mathematics, and general information. © 1990.