In this chapter I shall describe how, from working closely with others, I have come to view the nature and promise of mentoring. My beliefs arise from two periods of long-term collaboration, first with secondary school teachers then with university educators, as they engaged in educational research. In each period my role was different, but in neither period did I start with a clear notion of myself as a mentor. In the first period I acted as a co-researcher, in the second I saw myself largely as a ‘critical friend’. As I shall explain, however, I drew progressively on my experiences from each period in order to generate a perspective of mentoring that incorporates and extends both roles. I take each period in turn to present my view of what a university mentor should be.