摘要:This mixed-method study observes the effects of collaborative writing strategy on EFL learners’ writing skill and their perception of the strategy. The population consists of 80 students from a public senior high school in West Sumatra, Indonesia. The samples, which were selected by using cluster random sampling, were categorized as the experimental and control class. Each class were taught with different teaching strategies, experimental class was taught by using collaborative writing strategy and the control class was taught by using conventional teaching strategy. The data were collected through writing tests and interviews to measure the students’ writing skill and their perception of collaborative writing. The result of the analysis reveals that collaborative writing strategy has helped students in generating their writing ideas and activating the students’ background knowledge of the topics assigned to them to develop in their writings. The result of this study also highlights the students’ positive perception on collaborative writing strategy.