This thesis focuses on multilingual mathematics teachers in multilingualmathematics classrooms through the lens of professional identity. The aimis to increase the knowledge about the formation and development ofmultilingual mathematics teachers’ professional identities in relation tomultilingual mathematics teaching. A case study approach is adopted, inwhich Neda, a multilingual primary school mathematics teacher, and Aza,a multilingual mathematics teacher at the lower secondary level in Sweden,have been followed over two academic years.

The Patterns of Participation (PoP) framework is used as a conceptual andanalytical framework. As a conceptual framework, it enables theinterpretation of teachers’ professional identities through their shiftingexperiences of being, becoming, and belonging as multilingualmathematics teachers in multilingual schools and classroom interactions.Analytically, PoP enables the construction of several practices and figuredworlds relevant to teachers’ identities, as well as the illustration andconnection of practices and figured worlds significant for teachers inmultilingual classroom interactions.

The findings reveal that multiple, occasionally theoretically conflictingpractices and figured worlds are relevant for the teachers in relation tomultilingual mathematics teaching. A multilingual approach to teaching,as well as a language-focused approach to mathematical concepts andcommunication, is emphasised. However, the use of students’ mothertongue is less visible during classroom interactions. Teachers balancebetween the use of students’ mother tongue and the language ofinstruction, especially during interactions with newly arrived mathematicsstudents.

Teachers’ identity trajectories over two academic years of school change,though, highlight the teachers’ shifting experiences of being a multilingualmathematics teacher more than being a multilingual mathematics teacher.The cases make visible that teachers being or becoming recognised asqualified and successful mathematics teachers shift positively when theirsense of belonging is aligned within the school and among colleagues.Experiences of being, becoming and belonging as a multilingualmathematics teacher in the school are linked to the teachers’ professionaland educational language-related and multilingual experiences in the past.

In conclusion, being a multilingual mathematics teacher is entangled inteachers’ professional experiences and educational realities, whichforeground the official language of instruction for multilingualmathematics teaching. However, the identity development of multilingualmathematics teachers in schools can be enhanced by embracing theirexperiences and expertise as both multilingual and mathematics educators.