(to be revised)At the end of the interwar period, Belgian architecture critic Pierre Bourgeois (1898–1976) remarked: »Architects and engineers don’t know each other.« The word ›sufficiently‹ should be understood in this phrase, as Bourgeois evaluated the increasing rapprochement between both professions in order to face the new technological challenges in building. By the end of the 1930s, various complex projects as well as discussions in Belgian architects’ and engineers’ journals had put the intensifying collaborations between architects and engineers on the agenda. However, to both professions the challenges of designing and building in the interwar period in Belgium were determined by harsh and pervading socio-economic conditions: the difficult reconstruction after World War I and the economic crisis of the 1930s, calling for a reduction in building costs and causing even straightforward unemployment in the sector. Simultaneously, the debates leading to the law on the recognition of the diploma of architect (1936) and the protection of the free profession of architect (1939) took place. It is in these discussions that diverging ideals on the relation between »technology« and »art« are made explicit, just like on the desirable collaboration between engineers and architects. Different than for architects, the profile of the consulting engineer as an independent expert in building was already established in Belgium since 1913 and in the interwar period, engineers commonly signed articles and plans as such. Amidst of these economic and legal issues, the question on how building design should deal with new, scientific insights in engineering, with the rising potential of steel construction elements and of reinforced concrete, but also with the increasing standardization and commercialization of building elements was a challenge common to both architects and engineers, and not only in Belgium. Irrespective of schools and styles, a general idea among architects was that they should rely more on engineers’ skills, ...