The structure of socio-culture encouraged the following study to investigate the ways participation in collaborative learning tasks can have an effect on the overall English proficiency of EFL students’ academic achievement. The learners’ engagement in learning and collaboration with others for achieving their goals often happen in participatory approach to second language teaching and learning (Cobb, 1994; Greeno, 1998). In a same way, collaborative learning plays a good role in increasing learners’ interdependence (Bruffee, 1999), responsibility (Totten, Sills, Digby, & Russ, 1991), interpersonal skills (Rymes, 1997), and cognitive and critical thinking skills (Johnson & Johnson, 1986). Therefore, both the control and study group were randomly selected from 60 Iranian EFL learners of two intact classes. The first group which was the control group was exposed to regular teaching process through the conventional book-based method. While, in experimental group activities such as role play, problem solving, group work and collaborative tasks in the classroom instruction were mostly used. Accordingly, scores on the IELTS posttest in both groups improved but, the statistics of their overall performance showed that there is no significant difference. However, separate skills on the IELTS exam needed some analyses the result of which contended that the scores of experimental group on the speaking skill was significantly higher. Clearly, the scores on the vocabulary and grammar posttest in experimental group were significantly higher. In conclusion, higher mean scores indicate that EFL learners’ vocabulary and grammar learning will be facilitated through both participatory approach and collaborative activities. In fact, the more interactions among learners in classroom activities are used, improvement of speaking skills can be encouraged. As the results of the students’ and teachers’ interview revealed, both students and teachers’ attitudes towards participatory approach were positive and were also highly inclined to receive such tasks and activities in future
