The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides supplemental foods, nutrition education, breastfeeding support, and referral to other services for pregnant and postpartum women, and infants and young children. The objectives of the program include but are not limited to: improving fetal growth and development, improving the health and development of infants and young children, and increasing access to needed services. This report summarizes the research literature published since the last major review of the effectiveness of WIC in meeting these objectives.