Effective teachers require a variety of skills, including the ability to provide and incorporate feedback from others. Self-review and peer review are two methods that help preservice teachers develop feedback skills. Teacher educators face a number of challenges utilizing peer and self-review within their courses, especially in large university classes where preservice teachers of different majors are enrolled in the same course. Online peer review tools offer a promising approach to support peer review in preservice teacher education. Guided by adult learning theory, an experimental study was conducted to determine the effect of online peer review, using the peer review tool Peermark™. Preservice teachers in the experimental group used online peer review to provide feedback to peers about the creation of a content specific graphic organizer. Results show that online peer review resulted in higher quality graphic organizers when compared to self-review. Limitations, implications for practice, and future research suggestions are discussed.