Although there is intense debate about the effect of increased expenditure on education in developed countries, there is widespread consensus that provision of textbooks can substantially increase test scores in developing countries. This paper evaluates a program through which a Dutch non-profit organization provided textbooks to 25 rural Kenyan primary schools that were chosen randomly from a group of 100 candidate schools. After one school year, average test scores did not differ substantially between program and comparison schools. However, for those students in the top quintile of the distribution of initial academic achievement, the program raised test scores by at least 0.2 standard deviations.