This study explored the variations in peer review comments provided by L2 writers of high and low proficiencies. Two sampling procedures were used. First, convenience sampling was used to locate a college essay composition course as the setting of the study. Second, purposeful sampling was used to identify high-and low-performing writers as the subjects, from whom the peer review comments were collected and analyzed. An instruction-learning cycle on argumentative essay writing was conducted for 4 weeks. Each student was subsequently provided with the same sample argumentative essay and a peer review form to conduct the review. The rubrics on the review form included introduction, support for position, sequence, refutation, conclusion, voice, and grammar and spelling. Content analysis was conducted to compare the manner in which the comments varied among students of different writing proficiency levels. The results indicate that, although identifying problems was the dominant comment type of both high-and low-performing writers, high-performing writers tended to provide more details when explaining the identified problems and offering suggestions for revisions. The findings are discussed regarding the implications to peer review training.