The mission of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is to safeguard the health of low-income women, infants, and children up to age 5 who are at nutritional risk. WIC provides nutritious foods to supplement diets, nutrition education, and referrals to health care and other social services. Administered by USDA's Food and Nutrition Service (FNS), the program has grown rapidly since its establishment in 1972, and is now one of the central components of the Nation's food and nutrition assistance system. Almost half of all infants and about one-quarter of all children 1-4 years of age in the United States now participate in the program. Federal program costs were almost $4 billion in fiscal 2000, making WIC the country's third-largest food assistance program in terms of total expenditures. WIC accounts for almost 12 percent of total Federal expenditures for food and nutrition assistance. This report presents comprehensive background information on the WIC program-how it works, its history, program trends, and the characteristics of the population it serves. It also examines issues related to program outcomes and administration. How the WIC community responds to these issues may have a large impact on future program operations.