A study sought to add some baseline data specifically on the mentoring of school principals. It focused on a structured mentoring program run by the National Institute of Education of Nanyang Technological University in Singapore, through the perspective of the mentors and proteges. The mentoring program has been in operation since 1984. It appears to be working, but it is not clear what is working. The study set out to gather information on 2 basic questions: 1. How was the mentor/protege relationship formed and how did it progress? 2. What were the benefits of the structured mentor/protege relationship to the mentoring principal and the trainee principal? Some 36 mentors and 44 proteges participated in the study. The study concluded that: 1. the mentor/protege relationship is best initiated in an informal relationship away from the school, 2. mentors should clearly communicate their expectations, 3. mentoring relationships move through development and interpersonal stages, and 4. the benefits of the relationship are reciprocal. Copyright © 1993 MCB University Press Limited.