Undergraduate peer mentorship has the potential to transform mentor and mentee alike. In an effort to understand the potential positive effects of a peer mentorship program on honors peer mentors, paired sample t-tests of data from a pre-test/post-test of at least 69 honors first-year seminar facilitators shows that respondents grew in their leadership efficacy and teaching efficacy. Mentors also show modest gains in their sense of belonging to the honors program. Qualitative analysis of assessment discursive data further indicates that the yearlong facilitation experience is a mechanism for mentors' growth. Results indicate that being a peer mentor is a powerful means of fostering student development across multiple dimensions, including leadership efficacy, while meeting the goals outlined by a transformative honors educational experience.