Knowledge exchange, or peer-to-peerlearning, is a powerful way to share, replicate, and scaleup what works in development. Development practitioners wantto learn from the practical experience of others who havegone through, or are going through, similar challenges. Theywant to be connected to each other and have ready access topractical knowledge and solutions. When done right,knowledge exchange can build the capacity, confidence, andconviction of individuals and groups to act. Examples ofthese direct results or intermediate outcomes from aknowledge exchange include: i) technical water specialistsin several sub-districts of Bangladesh learn new skills toreplicate good practices (shared by their peers) forbuilding and maintaining a safe water supply; ii) dairysector and ministry of agriculture officials in Tanzaniareach agreement on a blueprint of potential dairy sectorreforms because of a new shared understanding and improvedcollaboration; and iii) farmers in Kenya adopt an innovativerice growing methodology, System of Rice Intensification(SRI), to increase the yield from their land after learningfrom the experience of countries that pioneered thismethodology. This edition contains a full revision of theoriginal art of knowledge exchange as well as new chapterson implementation and results. It draws lessons from over100 exchanges financed by the World Bank South-SouthFacility, analytical work conducted by the World BankInstitute and the Task Team for South-South Cooperation, andreflects the experiences of dozens of World Bank Groupstaff, learning professionals, government officials, andother international development practitioners who havebrokered and participated in South-South knowledge exchange activities.