Corrective feedback refers to a teacher or student’s reaction to a learner’s target language production containing an actual or perceived error. The last three decades have witnessed a large amount of research on the impacts of various types of corrective feedback on students’ written production. Along the same vein, the present study seeks to explore the effectiveness of providing teachers’ metalinguistic feedback vs. peers’ collaborative feedback on students’ writing performance. In so doing, the present study adopted a pretest-posttest quasi-experimental design including three upper-intermediate groups (i.e., two experimental and one control). The participants of the study were a total of 62 English as a foreign language (EFL) freshman students from two public universities in Tehran, Iran. The writing tasks utilized in the present study were adopted from IELTS writing Task 2. The results of one-way between groups analysis of variance (ANOVA) revealed that students produced significantly more lexically diverse as well as grammatically accurate language as a result of both treatments. Moreover, it was observed that collaborative peer feedback led to significantly higher lexical diversity than those of other two groups. The findings of the present study suggest that L2 teachers can opt for a combination of corrective feedback strategies to help learners improve their writing performance.
