This document reviews the interventions, such as policies, programs, and projects, that have been implemented by governments, donors, and other institutions to increase girls' access, persistence, and achievement at the primary school level. It examines both the formal system of primary education and nontraditional, alternative approaches to reach out-of-school girls. Its goal is to identify the strategies, practices, inputs, and factors that have had measurable impact in improving the availability and accessibility of basic education to girls in developing countries. The monograph employs an analytic model that categorizes interventions according to whether they address supply side (school factors) or demand side (household factors) barriers to girls' educational participation. On the supply side, few national policies are aimed at promoting girls' education. Educational expansion has limited effectiveness. At the program level, efforts are aimed at bringing schools closer to girls, making schools culturally appropriate, and helping girls learn. Textbooks, female teachers, and single sex schools may improve participation. On the demand side, interventions have attempted to lower the costs to parents of daughters' education and convince them of its benefits. Nontraditional approaches have succeeded in reaching girls prevented from attending school because of poverty and isolation. This paper concludes that, in addition to making school places available, schooling must be made accessible to girls. Multidimensional approaches to girls' education that take into account local context and both supply and demand factors have proven most successful. Selection of interventions should follow a logical process of development, based on needs assessment, monitoring, and evaluation. (DK)