This dissertation deals with the analysis of the establishment and the evolution of banking supervision in Switzerland between 1914 and 1971. It also includes an international comparison with a second case study: the development of banking supervision in Belgium during the same period. To that end, it relies on a wide collection and analysis of public and private archives, mostly unpublished, in Switzerland as well as in Belgium. The underlying question is to understand the regulatory environment behind the strong growth of the Swiss banking sector during the 20th century.The first step is to examine the conditions for the emergence of federal regulation on the activities of banks (1914-1935). Indeed, it was only in the context of the deep financial crisis of the 1930s that the resistance of the banking community to a regulation at the national level could be overcome. The Federal Act on Banks of November 1934, drawn up under the decisive influence of the representatives of the main banks, established a very weak regulatory regime. It did not introduce a structural reform of the banking system, but merely codified practices that were often already in force. As for the organization of supervision, it relied on private auditing companies, designed to review the banks’ compliance with the legal requirements. The independence of these auditing companies from the banks they controlled was not guaranteed. The state authority created in 1934 – the Federal Banking Commission–, was limited to a subordinate role and oversaw the audit carried out by the private companies.In a second step, the dissertation focuses on the evolution of the activities of this new regulatory body – the Swiss Federal Banking Commission – over a period of approximately 35 years (1935-1971). The question is to understand how the choice of an organization with limited budgetary and staff resources, and also limited legal intervention powers influenced the type of regulation implemented during theperiod under review.The thesis gives several ...