As countries grow rich, education improves in many ways. The sector enjoys more resources for education per primary school-aged child, not because of bigger budget allocations, nor an easing of the demographic burden on the system, but because the cost of inputs, especially teacher salaries, decline substantially relative to the per capita GNP. The extra resources enable countries to expand coverage and reduce the pupil–teacher ratio, with the latter receiving increasing emphasis during the past 20 years. The implicit trade-off against coverage raises questions about the efficiency and equity of education policies in developing countries, particularly in settings where significant shares of the primary school-age children remain out of school.