As increasing numbers of children in developing nations survive to school age, practitioners, researchers, and policymakers are increasingly focusing on the health and well-being of school-age children and on the possibility of using the infrastructure of the school system to deliver health and nutrition interventions. This research, conducted in Ghana through the worldwide Partnership for Child Development, identified and targeted school-age children's prevalent health problems; used simple, low-cost mass interventions through the schools; and developed partnerships for implementation between health and education, government, and non-governmental agencies. The specific intervention for this study focused on de-worming. Samples of 8- to 9- and 12- to 13-year-olds were obtained in 1994 at 3 intervention and 2 comparison sites for baseline, with subsequent samples selected for follow-ups. The results indicated that the interventions were effective in reducing infection levels of schistosomiasis and hookworm, reducing malnutrition, and improving achievement, though not necessarily improving students' attendance. The intervention effect on achievement was especially strong for nutritionally disadvantaged children and for girls. The feasibility of mass school-based treatment was demonstrated, with treatment provided to 85,000 children at a cost of $3.21 per child. Further research needs related to education policy were identified. (A list of the persons interviewed for the report is appended.) (KB)