Instructors may use low-cost, light-touch strategies to help students achieve optimal effort in demanding upper-level courses. The authors of this study exploit an intervention that provides a series of personalized feedback emails to students about their relative performance, which is tied to approving messages or tips that encourage improvement. The authors analyze the efficacy of this supportive rank feedback in an intermediate-level microeconomics theory course, given the challenges it poses to students. Evidence shows gains from feedback across the grade distribution, but they are short-lived and decline toward zero as the course progresses.