The story of independent evaluation in the World Bank is more than 30 years in the making. However, it is a story that has never been fully told. The Operations Evaluation Department (OED) of the World Bank will celebrate the thirtieth anniversary of its founding on July 1, 2003. This volume details this history of OED as related by many of those who participated in making that history and is divided into four sections. The first section is taken from a series of presentations made by former Directors-General, Operations Evaluations, and senior OED managers. The second part provides perspectives on OED from two of its most important internal constituencies - the Board of Executive Directors and senior World Bank management. Part three considers OED's relationship with external constituencies and finally, section four offers a forward-looking appraisal of the challenges of development evaluation from three of its leading thinkers.