This conclusion presents some closing thoughts on the key concepts discussed in the preceding chapters of this book. The book discusses some of the obstacles to extending the use of meta-analysis in social policy and explores welfare research. It suggests that ways of helping meta-analysis to become a more widely used, effective tool for policy evaluation. The book reflects on the aggregate evidence from meta-analysis of the United States (US) welfare-to-work evaluations and the retrospective study of the policy process leading up to the launch of the New Deal. It deals with the key findings of the meta-analysis before recalling the principal conclusions from the study of the process of policy-making and policy learning in the course of the design and implementation of the New Deal. The book explores the impacts of US welfare-to-work programmes, systematically taking account of available evaluation evidence by using meta-analysis.