This paper addresses three questions: (a) What is policy analysis? (b) How has policy analysis affected policy in a few cases? and (c) What tentative prescriptions can be made to improve the usefulness of policy analysis? Policy decisions with respect to the enactment of Medicare/Medicaid, the adoption of the all volunteer armed force, and the development of the Family Assistance Plan are reviewed to assess the role, if any, played by policy analysis. The role of analysis in incremental program change is also discussed. Some general conclusions are drawn from comparative analysis of these cases.