The major associations with the Special Supplemental Food Program for Women, Infants, and Children (WIC) in preschool children were better dietary intake associated with current WIC participation, especially for Fe, vitamin A, and vitamin C, but there were no increases in energy intake and, after infancy, no residual benefits from past WIC participation; strongest dietary effects among children who were poor, black, or in single-parent or large families (children lost to WIC were as needy as those currently enrolled); shorter stature, suggesting effective targeting (with enrollment in utero there was no parallel deficit in head circumference, which is consistent with results for newborns); better immunization and more frequent regular source of health care but no more frequent use of preventive health services; and better vocabulary with WIC participation begun in utero; better digit memory with entry into the program after the first birthday (differences that emerged only after statistical adjustment for sociodemographic factors); and more advantageous child behavior (NS).