In this article, we will examine some contrasted discourses on multilingualism that circulate nowadays in the field of education. Focusing on the cases of French-speaking Belgium and of the Franco-Ontarian community in Canada, we will show the existence of two discourses on multilingualism: one that insists on the positive value of multilingualism and that we consider as a consequence of social and economic changes brought by globalisation; and another that is much more a surrender of the purist conception of language rejecting "mixing" and hybridism and that seems to support resistance towards unwanted consequences of this globalisation movements (especially migration movements). In our view, these discourses on multilingualism are "ideological discourses" aiming at legitimating or contesting the impacts of global capitalism and post-nationalism. (Contains 36 notes.)