The aim of this study is to investigate a collaborative task conducted in an L2-German course for 2nd-year students (CEFR level A2) at Hiroshima University. In the weekly conducted tasks, two students provided each other with feedback on mistakes in their partners’ texts. The data collected in this study are based on 170 learner texts written for this purpose and 78 audio-recorded peer feedback sessions. The audio data were analysed qualitatively and quantitatively, evaluating whether mistakes were identified and corrected appropriately, and to what extent students used their L1 for performing the task. The results indicate that L2-German learners at CEFR level A2 are, on average, able to identify and correct their own mistakes in about 50 percent of the cases. In the peer feedback sessions they resort to their L1 to talk about grammar, to discuss problems concerning the task’s fulfilment, to ask partners for assistance, and to express their inner speech. In assessments it was noted that learners showed an improvement in their writing skills, an increased awareness of their L2 weaknesses and mistakes, and an increase in their vocabulary. Learning through peer interaction was generally regarded as beneficial, as it allows immediate feedback, awareness of mistakes, and spontaneous expression with a limited vocabulary. However, doubts concerning the appropriateness of peers’ feedback were also raised, with some students questioning why feedback on mistakes should be given in the L2 and whether the L1 might be more appropriate.