Abstract
Although writing is an important skill, the writings of many high school students in China in general lack cohesion and coherence. As the Chinese National English Curriculum Standards for High School (2017) mentioned, the cultivation of senior high school students’ discourse competence is of great importance. However, traditional teaching methods paid little attention to student writing at the discourse level. In recent years, collaborative writing has been introduced to writing classes, and most researchers examined its effect on students’ writing interests andwriting scores. The purpose of this study is therefore to investigate whether collaborative writing has a positive effect on students’ discourse competence. Specifically, it seeks to explore the effect of collaborative writing on students’ textual cohesion and textual coherence.Students’ writing assignments were analyzed using Coh-Metrix 3.0. Their interaction was analyzed through the perspective of sociocultural theory. The results showed that collaborative writing effectively promoted senior high school students’ textual cohesion and coherence. It also mediated their co-construction of knowledge about discourse through peer-peer scaffolding, which led to higher level of discourse competence.