The present study reports on a teacher's classroom-based research into the influence of proficiency-pairing on students' peer-mediated draft revisions. Three students of an EFL writing course at a Chinese university, who formed into peer dyads with their classmates voluntarily, participated in the study. Throughout the EFL writing course, they wrote five expository essays at different time points, had their EFL writing assessed by their peers, and revised their drafts based on the peer feedback received. Results showed that 1) When two students of high proficiency formed a dyad, a high-proficiency student's peer-mediated revisions were mainly about the global aspects of EFL writing; 2) When two students of intermediate proficiency formed a dyad, an intermediate-proficiency student's peer-mediated revisions were almost evenly distributed among the global and local aspects of EFL writing; 3) When a student of intermediate proficiency formed a pair with a student of low proficiency, the intermediate-proficiency student's peer-mediated revisions mainly centered on the local aspects of EFL writing. Implications are drawn for using multiple-peer groupings and fine-tuning teacher's feedback on the writing of students of differing proficiency in the Chinese EFL writing context.