This book reviews the scientific basis for nutrition risk criteria used to establish eligibility for participation in the U.S. Department of Agriculture’s Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). The volume also examines the specific segments of the WIC population at risk for each criterion, identifies gaps in the scientific knowledge base, formulates recommendations regarding appropriate criteria, and where applicable, recommends values for determining who is at risk for each criterion. Recommendations for program action and research are made to strengthen the validity of nutrition risk criteria used in the WIC program.