This article on the effect of globalization and superdiversity on language practices in Montreal and Brussels focuses on the sociolinguistic making of two francophone metropolises both affected by language contact resulting from historical development and contemporary migrations. After an overview of the changes in the linguistic market dynamics and a presentation of language planning issues, the article provides an analysis for each metropolis. The language practices are approached from three angles: the speakers’ linguistic repertoire, the description of language use and the analysis of linguistic attitudes and representations. An emphasis is put on the contribution of speakers associated with cultural diversity to the local sociolinguistic dynamics.