Online peer review has been increasingly implemented in composition and second language classes. This article reports on a pedagogical practice in which students used the Turnitin PeerMark tool to conduct peer response in a first-year writing class. In this study, students drew on multiple PeerMark functions (i.e., commenting tools, composition marks, and PeerMark questions) and provided feedback on their peers’ summary and response papers. In addition to students’ positive attitude toward the use of PeerMark revealed in the interviews, analyses of archived PeerMark records suggest that students provided constructive feedback in multiple aspects and that the majority of peer comments were later incorporated into students’ revisions through different ways. This report expects to encourage teachers to implement peer review using Turnitin in their classrooms and further explore the role of technologies for peer feedback.