In this paper we utilize the qualitative research method of phenomenography to explore what Ph.D supervisors understand research supervision to be and how they enact this understanding in the practice of supervising doctoral students. In total twenty phenomenographic interviews, designed to uncover the 'lived' experience of Ph.D supervision, were undertaken with supervisors of doctoral students at three Australian universities. Five qualitatively different ways of conceiving a supervisor's role emerged from the analysis of the interview transcripts. Supervisors expressing the conception of Quality Assurer seek the outcome of a completed Ph.D free of fundamental flaws. Supervisors expressing the conception of Supportive Guide also desire a completed Ph.D but for these supervisors, completion is achieved through nurturing, encouraging and supporting the student. Supervisors expressing the conception of Researcher Trainer seek to develop a future autonomous researcher and see supervision as an apprenticeship. Supervisors expressing the conception of Mentor are concerned with developing insightful researchers in a specific research area and see supervision as a partnership. Finally, supervisors expressing the conception of Knowledge Enthusiast seek new insight and knowledge as they push the student on a journey of discovery. Our findings suggest that while supervisors undertake similar tasks in the practice of Ph.D supervision, different supervisors approach these tasks differently because of qualitatively different understandings of what supervision is. Therefore, fundamental changes in the practice of supervision can only occur through supervisors changing their underlying conception of what supervision is through reflection and experience.