In addressing the pervasive problem of hunger in the developing world, reliable information on food insecurity is essential for effectively targeting assistance, developing interventions, and evaluating progress. Yet arriving at an accurate and comparable measure of food insecurity remains a challenge. This report introduces new estimates of food insecurity based on food acquisition data collected as part of national household expenditure surveys (HESs). The report explores the extent and location of food insecurity, the scientific merit of estimates derived from HES food data, the differences between HES-based estimates and those reported by the Food and Agriculture Organization of the United Nations (FAO), and-ultimately-how HES data can be used to improve the accuracy of the FAO estimates currently used to monitor progress toward reducing hunger