The purpose of this study is to explore the effect of using collaborative techniques and activities on EFL students' writing performance. A total of 35 low-intermediate EFL students ranging from 15 to 18 years-of-age participated in this investigation. These participants were assigned into two groups: An experimental group (N = 17) in which writing skill was practiced through a collaborative writing syllabus; and a control group (N = 18) in which writing skill exercised individually in the classroom. In this study a pretest/post-test was run, also a paragraph rating scale was used for obtaining students' overall writing performance and their performance on different components of writing such as content, organization, grammar, vocabulary, and mechanics. The findings of this study revealed that using collaborative techniques and activities had a positive effect (p = 0.001) on overall writing performance of EFL students, and on writing components such as content (p = 0.003), organization (p = 0.001), grammar (p = 0.001), vocabulary (p = 0.008), and mechanics (p = 0.001). The results of this study shed light on the importance of using collaborative techniques and activities in L2 writing classrooms, which bears some implication for teachers and curriculum planners.