The use of mentoring has nowadays become a predominant practice for the professional placement component of pre-service teacher education programs. Research however has identified that being an effective teacher does not make you an effective mentor. The present research investigated the role of professional development in the preparation of mentor teachers for their mentoring roles. Specifically, this paper presents the findings of a pilot mentoring preparation course that engaged mentor teachers in developing their knowledge about the nature and process of mentoring and the roles of mentors and mentees. Data about changed understandings of mentoring and changed mentoring practices of the mentor teachers who participated were gathered. The findings presented here are intended to inform the development of future professional development courses for mentor teachers who intend to mentor pre-service teachers.