This paper describes a study exploring in-service (IS) and pre-service (PS) teachers' language ideologies about non-Spanish-speaking students' multilingualism in Chilean classrooms. A survey was answered by 69 IS teachers and 34 PS teachers in the Chilean school system. Both groups were asked about two dimensions: (a) teachers' knowledge and training in L2 pedagogies and their ideologies about students' L1 and multilingualism; and (b) immigrant students' access and integration into Chilean schools. We focus on dimension (a); the results indicate that the teachers from the IS and PS groups do not consider that students' L1 is an impediment to the acquisition of the target language. They declare that the preservation of the L1 boosts non-Spanish-speaking students' self-esteem and can help them to acquire new linguistic knowledge. However, the results show a lack of consistent strategies to approach multilingual classes. These results are discussed in the light of the need to train teachers of all disciplines in multilingualism and the demand for public policies to teach Spanish as an additional language in Chilean schools.