This chapter focuses on challenge and reciprocity in researcher-student collaborative labour (Zigo 2001) in a large multilingual secondary school in Sweden. The school was recruited for a larger longitudinal study of classroom language policy. For the purposes of the present chapter, we analysed ethnographic data to shed light on the well-known challenge of recruiting and retaining students to participate in longitudinal research, and on aspects of reciprocity, which was opera-tionalized as benefits that both parties, i.e. students and researchers, needed or desired (Trainor and Bouchard 2013). Results show that of the 43 students who were present in the classrooms studied, 35 (81%) provided written, informed consent to fill in a language-background questionnaire and participate in an interview. Fewer students with low grades consented to participate, but those who did provided data no less rich than that provided by students with top grades. As to reciprocal benefits, the researchers secured the research data needed, but also new knowledge about students’ heritage languages and the multilingual territories they had left prior to settling in Sweden. Another benefit relates to empowerment. The researchers were empowered by learning culturally appropriate terminology to use when communicating about multilingual and multi-ethnic territories; and interview data suggest that students were empowered when positioned as experts on their multilingual repertoires and the language ecology in their prior home territories. Finally, the chapter reveals that researchers’ stance of reciprocity evolved organically over time through their ethnographic engagement in the classrooms.