While studies have shown that mentoring is essential to the development of new teachers, fewer investigations have examined what mentors learn about themselves and about mentoring through this role. In this study, the conversations between 13 mentors and their mentees were analysed, along with mentor self-evaluations and focus group data, over two years. Three questions framed the study: Is there a shift in mentor learning and development? How do conversations compare with the intended goals of mentors? How do professional development opportunities reflect in mentoring practice? Outcomes indicated that: professional growth was evidenced but varied among mentors; and a difference existed between the planned goals and actual content of mentors' conversations. Although professional development appeared to benefit mentors, shifting practice was by no means assured. Implications of the study for future research and for mentoring practice are considered.