A growing number of studies have shown that interteaching produces better student-learning outcomes than more traditional teaching methods such as lecture. But to date, no studies have directly examined whether interteaching is differentially effective for students who typically earn either good or bad grades in their courses. In this study, we alternated between interteaching and lecture several times during the semester and measured the exam performance of students with low, moderate, and high grade point averages. We found that interteaching improved the exam scores for students in each of these groups but that the improvement was most noticeable for students with low and moderate GPAs. Thus, interteaching may be especially useful for students who typically earn lower grades in their courses.