This research investigates how students from immigrant families whose first language differs from the language of instruction at school view themselves while at school, depending on the way in which they use their first and second language. While some immigrant students are inclined to predominantly use their first language in the home environment but their second language while at school (separate language use pattern, S-LUP), others use their first and second language across social settings (fused language use pattern, F-LUP). We expected self-views of immigrant students with S-LUP to more strongly depend on the immediate (language) context than self-views of F-LUP students. We content-analysed open self-descriptions which 569 adolescents with different first languages had provided in their second language, the language of instruction at school, while at school. As expected, compared to F-LUP students, S-LUP students' self-views contained more school-related descriptions, i.e., more self-descriptions bound to the immediate language context, but fewer home-related descriptions, i.e., fewer self-aspects bound to a first language context. Implications for language policies and educational practices in culturally heterogeneous schools are discussed.