Beginning in 1962, Section 1115 of the Social Security Act allowed the U.S. Secretary of Health and Human Services to waive specific provisions of the act within individual states, allowing them to implement welfare experiments or demonstration projects to reduce welfare recipiency, ease transitions into the labor market for welfare clients, or otherwise advance the objectives of the Aid to Families with Dependent Children (AFDC) program. The period between 1987 and 1996 was an especially active time for welfare reform waiver applications. Each Section 1115 waiver application required a plan for evaluating the effects of the proposed changes in the AFDC program. This period of active welfare reform and experimentation, accompanied by a rigorous evaluation component, held the promise of an unparalleled opportunity to examine and document the effects of proposed welfare reform measures. In this paper we review the Section 1115 welfare reform and evaluation activity conducted by states during the Bush and Clinton administrations, ending in August 1996 when the Personal Responsibility and Work Opportunity Reconciliation Act was passed by Congress. We base the review on publicly available data from the U.S. Department of Health and Human Services and on interviews we conducted with both state project managers and evaluators from each of the 44 states that had received Section 1115 welfare reform waivers between 1992 and the passage of the 1996 welfare reform act.