This paper examines the causes for deteriorating school enrollment rates in sub-Saharan Africa, particularly in primary education and especially for girls. The prevalent view that deterioration in school availability and quality are responsible for declining school enrollments in many African countries seems incomplete. Several studies suggest that a household sends children to school because education costs are offset by higher future earnings associated with higher educational attainment. There are direct costs, such as school fees, and opportunity costs, such as the earnings relinquished because the child is not working. Therefore, declining incomes and employment opportunities impact on household demand for education. The policy response to declining enrollments should not be restricted to building more schools and improving existing ones. Cost-reducing and demand-stimulating measures should be considered as well. Analytical tools can help policymakers assess which costs and benefits of education impact on household schooling decisions. Three studies of household demand for education in Ivory Coast and Tanzania are reviewed, which use very data-intensive regression analyses. A simpler, private rates of return analysis is suggested to identify constraining factors in educational demand. An appendix presents a detailed examination of primary school enrollments and opportunity costs in Madagascar from a gender perspective. Nineteen tables present data on school enrollment, return on investment in education by level and region, and time spent on various chores and employment activities. (Contains 81 references.) (TD)