The Basel Committee on Banking Supervision (BCBS) was established in 1974 as an informal group of central bankers and bank supervisors with the mandate to formulate supervisory standards and guidelines. Although the Committee does not have any formal supranational authority, it is the de facto global banking regulator and its recommendations have been widely implemented by member and non-member states. Maziar Peihani investigates the BCBS’s governance, operation, and policy outcomes to determine the extent to which it is and has been legitimate. The project is comprised of two parts. This part overviews the literature on the BCBS, outlines its contribution, and provides a primer on the Committee’s governance and functions. In addition, it engages with the current theories on legitimacy and discusses what legitimacy means for the global governance of banking and how it can be assessed.