Most studies on the impacts of the Food Stamp Program (FSP) and the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) have been based on research designs that compare program participants with nonparticipants. This approach has been subject to the criticism that selection into these programs is likely nonrandom and such comparisons may lead to either underestimates or overestimates of the programs' true effects. This project attempts to avoid these selection problems by taking advantage of the "natural experiments" that resulted from the programs' early expansion, when they became available at different times in different counties, to examine their health and longrun economic outcomes.

The FSP was introduced across counties over a 15-year period. The earliest county programs were established in 1961 as pilot programs. The program became voluntary in 1964, and all counties were mandated to offer benefits by 1975. WIC was first established as a pilot program in 1972, and, similar to the FSP, was introduced across counties over a number of years.