Abstract Over the last few decades, researchers and practitioners have acknowledged the social aspects of language learning. This study drew on Vygotsky's sociocultural learning theory to investigate EFL students' interactional dynamics during a collaborative revision activity. It also examined the impact of this jointly performed task on participants' writing performance. Participants included five pairs of EFL learners enrolled in an L2 essay-writing course at an Iranian university. Each pair attended one collaborative revision session during which they jointly revised their argumentative texts utilizing the feedback provided by their instructor. The researchers collected the participants' interactions during collaborative revision and their revised drafts. Data analysis revealed that students employed a variety of functions in their negotiations including scaffolding. It was also observed that scaffolding was mutual and both partners benefited from the joint revision task regardless of their level of L2 writing proficiency. These findings suggest that collaborative revision can be incorporated in EFL writing pedagogy as a method to improve writing and revision skills.