The object of this research is the co-building, maintaining and restoring of mutual understanding in face-to-face conversations. I study the way the participants of an encounter make sure that they give a common meaning to what they interpret. The first part of the thesis defines the key concepts and notions (the listener, the co-speaker - interprétant -, interpretation and mutual understanding - intercompréhension), it sets the conceptual back-ground of the work (constructivism and externalism), and it justifies the choice of the data used for the analyses. The corpus contains face-to-face conversations between administrative agents who are native speakers of French, and users, who are non native speakers. In the second part, I have studied the way agents help users build expectations, the way the listener shows that he is not satisfied with his interpretation, the way the speaker shows that he has identified a divergence between his interpretation and the listener's, and the way they negotiate meaning. I have also analysed the impact of the kinds of tasks performed on the behaviour of the participants. These analyses have brought to light a set of cues, of forms, of types of reactions and of strategies that have been used in the third part to propose contents, techniques and activities for the teaching of French as a foreign language and for professional training. This work has a general aim related to teaching and didactics: it suggests to reconsider the teaching of listening so that it becomes an object of teaching, and not only a means to teach.
