Improved birth outcomes appear strongest for women of Hispanic origin, with significant improvements in birthweight, gestational age, and LBW status, but with no changes in prenatal care. In general, the positive association of WIC participation and birth outcomes seems stronger for Blacks than for the White population, and even stronger when the Hispanic population is removed. Significant benefits are associated with WIC participation for unmarried women: improvements in birthweight, gestational age, LBW status, and adequacy of prenatal care. The trends appear similar to those for teenage women, many of whom also fall into this category. An inverse relation between maternal education and improved birth outcomes is evident. Women with less than a high school education show significant improvements in birthweight, LBW status, and adequacy of prenatal care. Stratification of the sample by birth parity revealed no consistent pattern.