The author describes her 30 years of experience in the design and conduct of a series of large-scale randomized controlled studies in the field of public welfare. She describes how these studies came about, what lessons can be drawn about research methods, what was learned about the effectiveness of these programs (the National Supported Work Demonstration, the Demonstration of State Work/Welfare Initiatives, Aid to Families with Dependent Children, and Temporary Assistance to Needy Families), whether these studies impacted national social welfare policy, and what lessons can be applied from these studies to other fields. The use of randomized controlled studies is seen as the strongest research methodology to test large-scale social welfare policies.