Supreme audit institutions are nationalagencies responsible for auditing government revenue andspending. Their legal mandates, reporting relationships, andeffectiveness vary, reflecting different governance systemsand government policies. But their primary purpose is tooversee the management of public funds and the quality andcredibility of governments' reported financial data. Inthe past the World Bank and other donors often establishedparallel auditing systems for their projects, underminingdeveloping countries' supreme audit institutions, onwhose work they could not always rely. Equally problematichave been projects that encouraged performance auditing butignored basic weaknesses in financial management. In recentyears the Bank has tried to strengthen oversight agenciessuch as supreme audit institutions. This note is intended tohelp Bank staff appreciate the role and nature of theseinstitutions, particularly in managing public spending,ensuring financial accountability, and strengthening public institutions.