AbstractIntroductionWhile peer teaching is often seen as benefiting learners, it can also benefit peer teachers. One possible mechanism is by building peer teachers' evaluative judgement or their ability to judge the quality of work of selves and others. This qualitative interview study explores how specialty medical trainees build evaluative judgement through peer teaching. It also acts as an illustrative example of researcher positionality within a special series exploring facets of qualitative methodologies.MethodsSeventeen interviews with specialty trainees were recorded and thematically analysed, using qualitative description to stay close to the trainees' views of their experiences. We reflect on our positionality throughout.ResultsTwo thematic categories are interpreted: (1) Peer teaching as uni‐directional. (2) Reflecting on one's own practice through peer teaching develops evaluative judgement.DiscussionFindings suggest the significance of self‐scrutiny in response to teaching dialogues, learner cues or fixing problems, in order to develop evaluative judgement. With respect to positionality, reflection suggests the value of diverse teams, and the need for reflexivity due to the sensitising nature of expertise.