This study analyzed results of an NSF-funded project that used Calibrated Peer Review (CPR)™ to promote writing and reviewing skills. The specific focus of the study was whether students at different levels of performance showed improvement in writing and reviewing competency with repeated use of CPR. The study paid specific attention to progress made by initially lower performing students. The courses of nine instructors with a total of 789 students were included. Repeated measures analyses indicated that across different science disciplines and student levels, students showed improvement in writing skills and reviewer competency with repeated use of CPR. In addition, the difference in scores between high and low performing students decreased over time in both writing skills and reviewer competency.