In Sweden, tutoring in the mother tongue is a special support measure primarily intended for newly arrived students to facilitate their transition into the Swedish school system. Tutoring is premised on the collaboration between the class teacher, responsible for subject-related expertise, and the tutor, who contributes with knowledge of the student's mother tongue and previous context of studies. In this case study of class teachers' and mother tongue tutors' conditions for collaboration at a multi-ethnic primary school, six mother tongue tutors and six class teachers were asked about the purpose of their work, how it was organised, and what could be done to improve working conditions. Interviews with head teachers, and data on work organisation from observations, document study, and participation in meetings for a period of one and a half years supplemented the teacher interviews. The analysis focuses on whether tutors and teachers belong to the same or different Communities of Practice, based on shared concerns and opportunities for collaboration, as well as looking at the relative positioning of languages and teaching roles. Findings suggest that the degree of collaboration between tutors and teachers was not sufficient to allow tutoring to function in the way it is envisaged by national steering documents. Tutoring was instead based on the tutors' own knowledge of the subjects they taught. Recruitment of suitable tutors was difficult. However, conditions for collaboration and more effective tutoring in the schools could be improved with relatively simple support structures at the level of the municipality.