Aims This is a qualitative study exploring how consultant histopathologists determine diagnostic competence in their trainees.

Methods Semi-structured interviews were conducted with consultants and trainees and analysed using the Framework Method.

Results Five major themes emerged from the data: process, person, stage of training, trust and time. Within these major themes, there were multiple subthemes which reflect the complex, longitudinal nature of the judgement, as well as the knowledge, skills and attitudes which are most relevant to diagnostic competence. A conceptual framework is proposed to illustrate the judgement ecology, which is supported by anonymised quotes from interview participants.

Conclusions Our study is the first to explore in depth how consultant histopathologists determine diagnostic competence in their trainees. This is particularly important as histopathology is a unique medical specialty for which there is little evidence to support the current assessment strategies during training. The resulting conceptual model and findings from this study may help to form an evidence base to inform future assessment tools in histopathology.