In Vietnam, writing is considered the most challenging skill for English as a Foreign Language (EFL)students. These students encounter various kinds of problems in their writing process, from generating ideas to revising their tasks. Previous studies reveal that collaborative writing could bring students numerous benefits regarding their writing performance. The present study was conducted to examine the impacts of collaborative writing on EFL students’ paragraph writing performance and investigate their attitudes toward using collaborative writing in learning English writing. This research followed a mixed-method design, which lasted 15 weeks and was conducted with the participants of 80 EFL tenth-grade students in a high school context. Three research instruments namely the writing tests (pre-and post-test), questionnaires, and semi-structured interviews were employed in this study. The findings showed an improvement in EFL students’ paragraph writing performance after they had experienced collaborative writing. Moreover, the majority of EFL students also showed highly positive attitudes toward using collaborative writing in learning English writing. Finally, the suggested pedagogical implications of using collaborative writing in learning English writing are hoped to contribute to the innovation of teaching writing in the context of high school in the Mekong Delta of Vietnam. Keywords: paragraph writing, collaborative writing, EFL students’ attitudes