The use of the in coaching is on the increase. This qualitative study discusses the experience of a coach who taught herself to conduct, analyse and score the Subject-Object Interview (SOI) (Lahey, Souvaine, Kegan, Goodman & Felix, 2011). Using heuristic inquiry the study explored what is involved in learning to conduct the SOI with the aid of a written guide; how the coach and eight volunteers describe benefits and limitations of an autodidact approach to SOI (ASOI) and what would be the implications of using the ASOI in coaching practice for coach, client and the coaching profession. An important finding was that participants considered coach credentials and experience more important than their status as SOI practitioner. Trust between participant and coach emerged as key to a successful ASOI and timing of the ASOI, ethical issues and contracting are of crucial importance. An approach for the use of the ASOI in the coaching process is proposed, offering scope for further research and discussion.