The potential for improving household-level food security in sub-Saharan Africa through new agricultural technology is assessed in this report. The study focuses on a project in The Gambia which introduced mechanical pump irrigation and improved drainage for rain fed and tidal irrigation to some 7,500 rice farmers. Production in the project takes place under fully water-controlled conditions that provide two crops per year, and also under partly water-controlled conditions that provide only one crop. The study shows that rice yields comparable to the highest yields in Asia can be obtained in Africa (although there is a crucial need to reduce the high costs of African irrigation schemes). By selling rice surpluses, project participants raised their real incomes by an average of 13% per household. It was noted that even a 10% income increase leads to a 9.4% increase in food expenditures and a 4.8% increase in calorie consumption. However, the reduction of malnutrition in the project area cannot be solved through food supply and income increases alone; more effective rural health services and sanitation are also needed. The report also stresses the importance of involving women in the use of new technology, especially through increased access to credit. Another emphasis of the study is the very high substitution effects between irrigated crops and rain fed crops because of swift labor movements between them.