In this mixed methods study, we employed thematic analysis (TA) to examine peer mentors' perceptions of benefits, challenges, and roles they experienced as mentors, as well as benefits and challenges experienced by first-year college students. We also utilized quantitative student ratings to classify mentors as highly, moderately, or minimally supportive in order to determine whether any subthemes from the TA appeared more or less frequently across the three groups. Highly supportive mentors reported greater camaraderie among their seminar students and fewer unmotivated students, but also fewer opportunities to provide support to students. Moreover, mentors' and students' perceptions in the minimally supportive group were discrepant; mentors in this group consistently reported providing more support than was perceived by mentees.