The present quasi-experimental study aimed at investigating the impact of trained and untrained peer feedback on students' written comment types and writing quality. Significant differences were found in terms of comment types provided: trained students provided a significantly higher number of comments focused on organization and content (global aspects) than untrained students, who provided a significantly higher number of comments based on grammar, vocabulary, and punctuation (local aspects) than trained students. However, the results of the study showed no differences in terms of increased writing quality between the trained and untrained groups, with both groups showing significantly higher writing quality in the final draft as compared to the first draft.