The present study examines the extent to which a cooperative mode of learning can influence writing outcomes of EFL university students. It employed an eight-week training program based on cooperative learning (CL) which utilized group work activities and assigned active roles to each member of the group for most of the sessions. There was a control and experimental group; both of which were homogenous intact groups with intermediate to advanced levels of writing. The total sample size for the treatment and control groups was 52 and evenly distributed for each class with 26 participants each. All participants were Applied Linguistics and Language Studies majors in their third-year writing class at the undergraduate level. As the primary resource to measure the writing outcomes of the participants, the researcher administered a mock International English Language Testing System (IELTS) writing task two and applied the standardized rubric (public version) to each writing sample. In order to gauge the effectiveness and to triangulate written test results of the learner training program, participants were surveyed using a 16-item Likert scale, and, bottom and top achievers were interviewed using a series of in-depth queries. The findings from the study reveal statistically significant results when analyzing the gains made by the participants in the treatment group through improved writing scores. Posttest results of the treatment group show an average increase of almost a full band on the 0 to 9 IELTS scale. In addition, the participants primarily attribute improved writing as a direct result of the learner training program using CL. The general positive perspectives of the participants towards the cooperative mode of learning and improved scores indicate that CL is a viable alternative to teaching writing in an EFL context.