This article sets out from the observation that internationalization and contextualization of scientific knowledge increasingly appear to be in conflict, raising the question of the part played by language in the construction, transmission and dissemination of such knowledge. We will start by emphasizing the importance of considering language not just as a communication tool (vehicular function) but as a construction tool (constitutive function). We will then show how the two functions may be presented differently according to the nature of (a) the disciplines involved (natural sciences, humanities, etc.) and (b) the activities observed (teaching, popularization, international publication, etc.). Finally, we will examine the question of language and multilingualism in the assessment of scientific research, and in particular will describe the postures adopted by research advisers in various disciplines. This will enable us to conclude with some reflections on language policy in higher educational and research institutions.