The experiences of first-year, first-time college students are impacted by a variety of challenges that pose a threat to student success and retention. One intervention universities are implementing to address these challenges are peer mentorship programs. While the benefits to first-time students of peer mentorship programs are well-researched, there is a lack of research on the benefits for mentors themselves. The purpose of this study was to examine the perceived and demonstrable benefits for peer mentors working within a first-year seminar. This mixed-methods study assessed both first-time student achievement outcomes (i.e., N = 7,154) as well as the professional and personal development benefits of peer mentors (n = 52). Results showed first-time students who participated in the peer mentor program had significantly higher student achievement and peer mentors themselves had increased academic self-efficacy, improved communication, leadership, and interpersonal presence, and strengthened social and professional networks.