The 1983 revised USDA thrifty food plan is used as the basis for benefits in the Food Stamp Program. The thrifty food plan is the lowest cost food plan of 4 developed by the Human Nutrition Information Service (HNIS). The quantities of different food groups needed by a household to provide a nutritious diet are specified. This food plan contains large proportions of foods which are economical sources of nutrients. Quantities of the 31 food groups are recommended for different sex and age groupings. Changes in the thrifty food plan were necessitated by: changes in dietary standards; new information on nutrient content in foods; more information on actual consumption statistics; shifts in food prices; and changes for older adults which were needed to remain consistent with RDA groupings. Data and procedures used to revise the plan are discussed. A number of tables outline the information presented. Four procedures used to estimate the cost of foods in the plans each month are listed. The 4 food plans are an on-going project for USDA and are changed or modified as costs change and information about nutrients and food habits becomes available. (kbc)