The Special Supplemental Food Program for Women, Infants, and Children, popularly known as WIC, provides participants with supplemental foods and nutrition education. The WIC participants are eligible pregnant, postpartum, and breast-feeding women, infants, and children up to their fifth birthday. The program currently serves 1.2 million infants each month. The U.S. Department of Agriculture National WIC Evaluation Study of Infants and Children is the most comprehensive assessment of WIC's impact on a national infant sample. Its findings indicate that WIC infants consumed more iron-fortified infant formula (the core of the WIC infant food package) than non-WIC infants and, as a result, had higher daily intakes of formula-related nutrients--namely, iron and vitamin C. Because of lower consumption of whole cow milk, WIC infants had lower daily intakes of milk-related nutrients--calcium, protein, magnesium, and vitamin B6. The research team concluded that increased dietary intake of specific nutrients occurs only during program participation and has no residual effect after participation ceases. Possible scientific and social science research that would be useful in federal policy decisions affecting infant participation in the WIC program is discussed.