This paper explores how students in an Educational Psychology subject in a university L2 immersion context accomplish learning, mobilise their plurilingual repertoires and restructure their participation in carrying out a teamwork task over the course of approximately one week. The study is novel in several ways. First, it aims to fill a gap in the literature by exploring dynamics of knowledge construction in a multilingual, "internationalised" university classroom, a context that is currently underrepresented in research, although increasingly common in practice. Second, the theoretical-analytical framework, inspired by socio-constructivism and conversation analysis, lends support to both situated and longitudinal arguments for learning; perspectives that are often examined separately in interactionist literature. Finally, the framework is used to seek evidence of knowledge construction not only in terms of the second language but also in terms of disciplinary content and by paying particular attention to how students participate and use their available languages in managing the different task stages. The results not only demonstrate the utility of the proposed framework but also highlight how the mobilisation of plurilingual repertoires may be advantageous for learning and participation in similar higher education classroom settings and, ultimately, for doing internationalisation.