A new era of social welfare policy began in 1996 with passage of the Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA). The Aid to Families with Dependent Children (AFDC) program, a federal entitlement with many national standards for assistance to low-income families, was replaced by the Temporary Assistance for Needy Families (TANF)program, which provides a fixed block grant to state-administered programs. The passage of the federal welfare reform legislation signals a major shift in responsibility for the design, administration and evaluation of support programs for low-income families. As states explore the opportunity for the development of policies and programs that respond to local needs, there is a growing awareness of the lack of appropriate data to evaluate the effectiveness of welfare programs and to monitor the well-being of families as they enter, participate in, and exit the welfare system.