With the dissemination of a process-oriented approach to teaching writing, collaborative learning, which enjoys a constructivist theoretical foundation, has found its place in most writing classes and has shed light on interesting issues . This piece of research seeks to examine the impact of incorporating collaboration into Iranian EFL writing classes. The participants were 120 Persian-speaking English major students taking their writing courses, and 26 writing teachers, with minimum three years of experience teaching writing at university level. Data were gained from two pre-and post-course student and a teacher questionnaire surveys in order to evaluate the usefulness of different tasks and teachers perception of student preference, respectively. The findings indicated that the participants welcomed collaboration. There was not a high degree of correspondence between teachers perception of students preferences and their actual preferences. If carefully planned, implementation of collaboration, a concerted endeavor made jointly by the students, would allow for an interaction that is meaningful, authentic and supportive.