This article examines the sociolinguistic competence of French immersion students. We first present an overview of the range of variation found in L1 speech and make a distinction between vernacular, informal, formal, and hyper-formal variants. We then compare the use of these forms in the speech of Canadian francophones and Grade 9 and 12 students enrolled in a French immersion program. Our analysis shows that the immersion students' sociolinguistic competence is lacking in that they rarely or never use vernacular and informal variants and overuse forms that are formal or hyper-formal. In order to address this shortcoming, we propose a pedagogical methodology for improving students' sociolinguistic competence, concentrating in particular on the need to increase students' use of informal variants (e.g., ne deletion and /l/ deletion) and to decrease their use of hyper-formal ones (e.g., the verb habiter and subject pronoun nous).