This contribution gives an account of how concrete construction developed in French-speaking Switzerland since the end of the nineteenth century. The narrative is based on original sources from the Archives de la construction moderne (Acm) and on data and facts from local technical literature. Most attention is paid to reinforced-concrete frame structures. This method of construction had been well-rooted in French-speaking Switzerland since Samuel de Molin became a dealer of the Hennebique system in Lausanne in 1892. Hidden behind cut-stone facades (Jean Taillens and Charles Dubois, UBS Building, Lausanne, 1922) or skilfully exposed (Fernand Dumas and Denis Honegger, University of Fribourg, 1937–1941; Marc Piccard, College du Belvedere, Lausanne, 1952–1965), the reinforced-concrete skeleton was a capital resource for architects and engineers, and was developed over the decades, under the influence of cultural, technical and formal factors.