This report is a comprehensive review of country experience with Medium Term Expenditure Frameworks (MTEFs) worldwide. It looks at countries both with and without MTEFs over the period 1990 to 2008 to obtain results about their impact on fiscal performance. The report is structured as follows. Chapter two provides background on what constitutes a MTEF and what it aims to achieve. It also describes the Bank's engagement with MTEFs, presents main points of debate over the experience with MTEFs, and provides a rationale for this study. Chapter three describes the key characteristics of MTEFs, explains the approach used to identify and classify them according to their stage of development, and reviews trends in their adoption. Chapter four outlines the methodological approaches used to examine the impact of MTEFs on fiscal performance, formulates the research hypotheses that are tested in the study, and presents empirical findings from the event studies and econometric analysis. It also presents qualitative insights, informed by case studies, on how MTEFs have affected the quality of budgeting. Chapter five draws some lessons about the key institutional determinants of MTEF performance. Chapter six discusses lessons learned from Bank support for MTEF implementation. Finally, chapter seven presents the conclusions of the study and discusses their implications for the Bank. Several appendixes provide supporting material, including a country-by-country tabulation of MTEF status, a full discussion of econometric results, and country case studies.