Summary: GAO commented on the federal government's ability to assess the goals of the Temporary Assistance for Needy Families (TANF) program using national, state, and local data. These data address the goals to differing degrees. National data, which includes data collected in national surveys and information that all states report to the Department of Health and Human Services (HHS), include extensive information on TANF's two goals of providing assistance to needy families and ending dependency on government benefits but have limited information on promoting family formation. The data pertain to such issues as changes in TANF workloads, recipients' participation in work activities, employment status and earnings, and family well-being. Although there are national data on the incidence of out-of-wedlock births and marriage among TANF recipients and other low-income families, these data include only very recently available information on states' strategies to prevent out-of-wedlock pregnancies or promote family formation. Studies of welfare reform at the state and local levels contain the same kind of information as national data, but they also include information about areas very recently covered by national data. Much of these data come from waiver evaluations--evaluations conducted in states that experimented with their welfare program, under a waiver from HHS, prior to TANF. The usefulness of existing data for assessing TANF's progress varies. In general, the need for information about TANF's progress will have to be balanced against the challenges of rigorous data collection from the low- income population.