<p>The main goal of education is to create autonomous lifelong learners who have the ability to acquire the knowledge and skills necessary for their future life. Constructivist theories of learning, especially current popular approach, communicative language teaching recommends creating cooperative learning situations in all kinds of educational context in order to achieve this goal. To empower students as self-regulated and collaborative learners, peer feedback is increasingly applied in process approach to teach writing. Thus, the circumstances under which peer feedback is beneficial for students&rsquo;improvements are worth to be investigated in detail. Especially, the students&rsquo; emotional state can mediate the impact of peer feedback on their performance. The results obtained may be informative for EFL writing teachers in terms of the aspects to take into account when implementing feedback in order to foster the development of students&rsquo; positive attitudes toward it.</p><p><strong>Keywords:&nbsp;</strong>Peer feedback, Writing skill, Cooperative learning.</p>