This qualitative study explores how native peers as teaching assistants can support language learning in Higher Education. The data of five semi-structured group interviews of 15 teaching assistants in total were analysed thematically. The results indicate that the assistants embraced multiple roles during the programme and within the lessons. However, in the role of a peer student who collaborated on an equal level with the learners, they could best facilitate learning and communication. As native speakers, they complemented the teacher's expertise by their regional and up-to-date cultural and linguistic knowledge. This article supports a wide view of mediation adopted by the CEFR Companion Volume and focuses on its two mediation activities. The so-called didactic triangle was used to illustrate how native peers mediated between the teacher, the student and the subject to facilitate the language learning process. The assistants acted as mediators in different ways, interculturally and pedagogically. Nevertheless, a few assistants experienced challenges when assisting at lower CEFR levels. Thus, it is essential to discuss roles and expectations as well as the process together with the teachers, the students and the assistants.