Purpose: There are a number of issues that can prevent students from obtaining a college degree. Our aim is to support academic probation students to improve their grades through a peer mentoring program. Method: 29 students as peer mentors were enrolled to provide support for 35 academic probation students and 51 as control. All students participated in the 4 month-long program including mentoring twice a week and out of campus activities. To identify factors affecting the change in the participants’ GPA, a self-efficacy scale and an interpersonal support evaluation list were given to them before, as well as after the program. Using the SPSS/PC program, Chi-square test, paired t-test, ANOVA and lineal regression were applied. Results: All subjects significantly improved their self-efficacy and interpersonal support evaluation after the program (P<.001). The largest change in GPA after the program was shown in academic probation group (P<.001). Group, general self-efficacy, tangible help, belonging all were put into a regression model explaining the change in their GPA after the program (modified R squre is 69.5%, P<.05). Conclusion: A mentoring program, which aims to enhance self-efficacy and interpersonal support, can provide positive influences for a college student who needs a little extra attention from a peer.