Both ‘descriptive’ and ‘applied’ Translation Studies draw on the theoretical branch, on translation theory. But they do not make the same use of it. According to the author of the paper, this is particularly evident in the case of the concept he wishes to concentrate on, that of norms. It is a concept that has come to play a major role in Translation Studies of all kinds. The trouble is that it keeps cropping up at different levels. The rest of the paper, then, focuses on the role of norms in translation, seen as a communicative practice and therefore as a form of social behaviour. At the end the author returns to the place of the concept of norms, as an operational concept, in Translation Studies.