This article aims at a better understanding of the role played by multilingualism and language in general in the process of scientific knowledge construction. By analysing various cases of multilingual communication in different universities and subjects (marketing, physics, law), we propose to focus on two parameters: the language regime and the participation regime. Language regime is envisaged through different modes: language contrast (languages referred to for developing some topics in the subject) vs. language alternation (languages used as a medium of communication). An additional dimension is related to the fact that multilingualism occurs not only in oral interaction but also in writing. Participation regime is approached through the general opposition of monomanagement (teaching-oriented) and multimanagement (learning-oriented). In multilingual settings, generating a major process of negotiation is likely to stimulate the use of different languages and even to contrast languages in order to elicit some content issues. At the end of the article, we introduce the notion of didactic regime, which represents the way participants articulate language/multilingual resources and (more or less) collaborative formats in order to build up the subject knowledge. Such a regime might be decided through negotiation, proposed by the teacher or imposed by the institution.