Clinical supervision is crucial for the professional learning and development of practitioners in many fields. While many have articulated what should happen in clinical supervision, and evaluative research has been undertaken, little is known about the details of what actually happens in clinical supervision. This study addresses this gap, focusing on how professionals (psychologists) work with knowledge while collaboratively working through complex problems of practice. Six psychologists (three pairs) participated, audio-recording five supervision sessions, and giving two interviews each. Transcripts were analysed to uncover what was discussed and how problems were approached. Four ways of working with knowledge (epistemic practices) were found: recontextualising practice knowledge, recontextualising theoretical knowledge, story-telling, and asking expansive questions. These highlight important features of professional supervision practice that have not previously been approached theoretically as epistemic practices.