Summary: 'Decentralization in Client Countries' assesses the effectiveness of Bank support for decentralization between fiscal years 1990 and 2007 in 20 countries, seeking to inform the design and implementation of future support. Given the difficulties of measuring the results of decentralization, the evaluation uses intermediate outcome indicators-- such as strengthened legal and regulatory frameworks for intergovernmental relations, improved administrative capacity, and increased accountability of subnational governments and functionaries to higher levels of government and to local citizens-- to assess the results of Bank support in these 20 cases. To examine potential lessons at a sectoral level, the evaluation also assesses whether Bank support for decentralization improved intermediate outcomes for service delivery in the education sector in 6 of the 20 countries.