‘The Annual Review of Development Effectiveness 2009’ presents evidence on the World Bank’s efforts in two areas. Part I tracks the outcomes of Bank projects and country programs and the evolution of monitoring and evaluation (M and E). Part II examines the Bank’s support for environmentally sustainable development compatible with economic growth and poverty reduction. The Bank’s project performance rebounded in 2008, allaying concerns about the weakened performance in 2007. As previous ARDEs have shown, project performance has been improving gradually for 15 years according to the traditional measure-percent of projects with satisfactory (versus unsatisfactory) outcomes. But IEG ratings of M and E quality for completed projects indicate considerable room for progress. Information to assess impacts continues to be lacking although preliminary data suggests improvements in baseline data collection. Bank support for the environment has recovered since 2002 due to new sources of concessional finance. The outcomes of environment projects have improved in recent years. A growing number of regional projects are addressing the shared use of water resources. New global partnerships are deepening the Bank’s involvement in climate change issues. But M and E remains weak: three-quarters of environment-related projects-those managed by sectors other than environment-lack reporting of environmental outcomes.