This evaluation assesses the BankGroup’s effectiveness and comparative advantage in fosteringregional integration during FY2003–17 and draws lessons thatcan be used to inform future regional integrationoperations. Client countries of the World Bank Group haveturned to regional integration as one of the pathways towardfaster economic development and peace, and to help overcomedevelopment challenges. Main findings of the report include:(i) Overall, the Bank Group’s efforts to foster regionalintegration have led to mostly positive development outcomesin the Sub-Saharan Africa Region and in infrastructuresectors. (ii) Though the IDA Regional Window program hasalso contributed to regional integration (mainly in theAfrica Region), the development outcomes of itsinterventions are not significantly different from similarprojects co-financed outside the program.