This chapter arises from the study of a German language lesson at a primary school in Frankfurt/Main, Germany carried out in March 2017. This was one of the case studies conducted as part of the Joint Action in Didactics in Europe (JADE) project (Wegner et al. 2019) , which has cross-curricular foci on mathematics, physical education and first-language teaching in school. The theoretical framework for the study is based on the perspective of Bildungsgangforschung and -didaktik developed within the tradition of German didactics in combination with the concept of epistemic quality. The study focuses on the question of how the nature of epistemic quality in language and language use can be characterized and relates this to the three levels of interaction and co-operation in the instructional process that arises from consideration of Bildungsgangforschung and -didaktik. The analysis concentrates on the epistemic quality of the...