Web-based collaborative L2 writing promotes writing to learn and language learning by encouraging learners to exchange feedback and make decisions collaboratively (Zhang & Chen, 2022). However, learners may disregard feedback or disengage due to doubts about their language skills, peer feedback quality, or group dynamics, which limits learning outcomes (Hsu, 2019; Neumann & McDonough, 2015). Enhancing learners' engagement with peer feedback is crucial. This study explores the impact of collaborative inter-group peer feedback (CPF) on web-based L2 collaborative writing, focusing on feedback quality, co-written essays, and individual L2 writing improvement.

Participants included 42 EFL learners from two junior writing classes in a Taiwanese university. The classes were randomly divided into a CPF group and a non-CPF (NCPF) group. Over seven weeks, both groups completed pre- and post-test individual writing and two collaborative writing tasks using Google Docs. The CPF group exchanged collaboratively discussed feedback with another group during collaborative writing processes, while the NCPF group did not. Analyses evaluated the content, organization, and language accuracy of pre- and post-tests and co-written essays. Peer feedback was coded for focus (content, organization, language) and quality (critical vs. non-critical). Results aimed to shed light on CPF quality and its impact on the co-written essays and individual L2 writing development.