This paper synthesizes research on the acquisition of linguistic variation by learners of French as a second language--an overview that, to our knowledge, is the first of its kind. It also presents a case study on French immersion students' acquisition of the pronouns "nous" and "on" "we," an alternation in many varieties of spoken French. The study shows that the students use the mildly marked variant "on" slightly more often than the formal variant "nous" but much less often than native speakers (who use it almost categorically) and immersion teachers (who strongly favor it). Female and middle-class students favor "nous," students with greater extracurricular French language exposure favor "on," and students who speak a Romance language at home favor "nous." Various explanations are proposed for these correlations. Finally, the students, like L1 Francophones, favor "on" in linguistic contexts in which the referent is both nonspecific and unrestricted.