The peer mentor program at the two-year campus of New Mexico State University at Alamogordo utilizes a stress prevention model of social support. In an effort to determine the most successful program design, two social support models were introduced into the program. In the first, 14 participants received individual, one-on-one support from a mentor, while in the second, 12 students received support in small groups from a single mentor. A control group of 15 students received no support. In both support conditions, students met with the mentor for 1 hour each week to discuss the campus and student-related issues, or to study. All study participants were new to the college. The two different support conditions were compared to assess effects on mentees' grades, retention, identification with the role of student, and psychological well-being. In addition, the effects of mentor-mentee similarity, and the performance and psychological well-being of the mentors were examined. Pre- and post-intervention questionnaires were used to assess psychological outcomes. Study results included the following: (1) the mentored students had higher grade point averages (GPAs) than the students who had no mentors, regardless of whether the mentoring took place in group or one-on-one settings; (2) students who had been mentored in groups returned the following semester at a higher rate than students with individual mentors or students in the control group; (3) there was virtually no change in commitment to the student role in any of the groups; (4) similarities in the attitudes and activities of the mentors and mentees had no effect on GPA or retention; and (5) a detrimental relationship was found between mentor-mentee similarity and the GPA of the mentor. (PAA)