The process of internalisation of norms within different institutions is not homogenous, its speed and depth depending on several factors. Using the case of sustainable development in dams, this article analyses actors – here, dam promoters – whose institutional or disciplinary culture does not lend them to easily take these norms into account. The hypothesis is that the “identity” and the disciplinary or ideological capacity of these “technical” institutions play an important role in the internalisation of non technical, social, norms. This follows Young’s recent arguments concerning the role the internal structure of international institutions plays in internalising and spreading environmental norms.