This technical paper distills the emerging experience and lessons of Sector-wide Approaches (SWAps) in the health sector, supported by the World Bank and other Development Partners (DPs), in six countries: Bangladesh, Ghana, Kyrgyz Republic, Nepal, Malawi and Tanzania. It draws on the findings of Project Performance Assessment Reports (PPARs) conducted by the Independent Evaluation Group (IEG) on health SWAp support operations in Bangladesh, Ghana and the Kyrgyz Republic, and of field-based case studies that assessed the Bank's lending and non-lending support to Health, Population and Nutrition (HNP) in Malawi and Nepal, where SWAps are more recent. This paper also incorporates the findings of an evaluation of Tanzania's health SWAp, commissioned by the Government of Tanzania, and financed by DPs. The design, substantiation, and validation of the findings and lessons of this study have benefited from a review of the SWAp literature and vetting of preliminary findings and lessons with SWAp practitioners. This study grew out of the SWAp portfolio review and the distillation of health SWAp experience to date, undertaken as input to IEG's recent evaluation of the World Bank's support to HNP, improving effectiveness and outcomes for the poor in health, nutrition and population: an evaluation of World Bank Group support since 1997. The paucity of health SWAp evaluations in the literature, the richness and complexity of the preliminary findings, and the strong demand, inside and outside of the Bank for more distillation of SWAp experience and lessons all were justification for the undertaking of a more in-depth analysis.