Here Mother Tongue Instruction (MTI) in secondary school education for students with intellectualdisabilities is investigated. Earlier research shows that multilingual development may have positive effectson students’ development of language and cognition. The specific aim is to investigate what MTI in theadapted school for students with intellectual disabilities can be. The study builds on fieldnotes andrecordings from observations from eight lessons in one class, which is analysed based on aspects of space,activities and language use. The results show that the Arabic instruction was separated from the students’other education and the MTI teacher did not collaborate with other teachers at the school. Thus,opportunities for teachers and students to compare the two languages were few. The study also showed theimportance of collaboration between different categories of staff. The conclusion is that collaboration is anunused resource with potential to improve the learning conditions. Thus, more research is needed on howcollaboration could be developed for multilingual students between different teachers, such as MTI teachers,teachers in Swedish as a second language and special needs teachers.