This study investigated students' perceptions of collaborative writing in a teacher-centred class and their change in beliefs about English writing through collaborative writing experiences. The analysis of multiple data sources (i.e., video recordings of collaborative writing activities, two in-depth, semi-structured interviews, one stimulated recall interview and four response papers) from three selected participants revealed that collaborative writing was perceived as beneficial for improving writing, providing the opportunity to pool ideas and having positive emotional (e.g., reducing stress) and social effects (e.g., building a network). The participants were also concerned that it limited their actual learning and thinking, increased the difficulty of dealing with various views and provoked negative emotions (e.g., loss of self-confidence) and social effects (e.g., feeling isolated). In addition, the analysis of the students' beliefs about English writing before and after collaborative writing revealed their reconsideration of what good English writing involved (from focusing on vocabulary, sentences and grades to understandable texts), the purpose of English writing (from exam-­oriented purposes to communication purposes), the focus in English writing (from product writing to process writing) and the nature of English writing (from individual work to teamwork).