This study examines the peer review activity among high-level Japanese university students (an average TOEIC score of 675) in their EFL (English as a foreign language) writing class and explores the effects this activity can have on students’ cognitive processes in EFL writing. Based on Schmidt’s concepts, “noticing” and “understanding,” and Muranoi’s concept, “intake,” which are key concepts for discussing the cognitive processes in learning a second / foreign language, this study analyzes the students’ draft and revised essays, Peer-Editing Sheets (used when they wrote their comments about other students’ essays and their responses to their peers’ comments), and interviews. As a result, peer review can be considered to be effective for facilitating their EFL writing, because (1) it promotes “noticing” because people point out problems in their writing; (2) it deepens their “understanding” about how to solve their writing problems specifically; and (3) it motivates them to improve their essays so that others can understand them more clearly.