Although peer-mentoring relationships are critical to including youth with intellectual and developmental disabilities in postsecondary educational settings, little is known about the motivations and experiences of peer mentors. To investigate, we conducted a mixed-methods study in which 17 volunteer peer mentors completed the Volunteer Functions Inventory (VFI) and participated in interviews about their motivations and experiences. On the VFI, participants were motivated to volunteer to express personal values and to enhance their own understandings; to a lesser extent, they volunteered to gain career-related experience. Interviews revealed 5 themes: (a) friendships, (b) personal growth, (c) community involvement, (d) experiences with people with disabilities, and (e) future careers related to people with disabilities. Implications for research and practice are discussed.