Recent congressional initiatives seek to focus funds for certain federal social programs on interventions for which randomized experiments show sizable, sustained benefits to participants or society. The private, nonprofit Coalition for Evidence-Based Policy undertook the Top Tier Evidence initiative to help federal programs identify interventions that meet this standard. The Government Accountability Office (GAO) was asked to examine (1) the validity and transparency of the Coalition's process, (2) how its process compared to that of six federally supported efforts to identify effective interventions, (3) the types of interventions best suited for assessment with randomized experiments, and (4) alternative rigorous methods used to assess effectiveness. GAO reviewed documents, observed the Coalition's advisory panel deliberate on interventions meeting its top tier standard, and reviewed other documents describing the processes the federally supported efforts had used. GAO reviewed the literature on evaluation methods and consulted experts on the use of randomized experiments. The Coalition generally agreed with the findings. The Departments of Education and Health and Human Services provided technical comments on a draft of this report. The Department of Justice provided no comments.