What information is available to inform the planning of a nutrition research agenda for the United States and Canada? This question provided the backdrop for the Dietary Reference Intakes Research Synthesis project undertaken by the Food and Nutrition Board of the Institute of Medicine (IOM) of the National Academies. The Dietary Reference Intakes (DRIs) are quantitative reference values for recommended intakes and tolerable upper intake levels for a range of nutrients. They are used widely by dietitians in individual counseling, by federal nutrition officials in program and policy development, and by the nutrition research and education communities in government, academia, and industry.