Aim: To identify behaviours and attitudes that exhibit poor professionalism at the proto-professional stage of undergraduate health professions education, and investigate the extent and nature of agreement by faculty on appropriate responses by undergraduate students in the UK.Methods: A preliminary inventory of 69 items of behaviour and attitude was derived from literature review and 1-month observation at a UK teaching site. Reference Groups were formed by e-mail solicitation of senior medical educators in the UK and the Dundee Medical School to identify consensus on the relevant items and the appropriate responses.Results: The multi-stage study generated a preliminary inventory with 42 items and identified clear areas of consensus among faculty on appropriate responses by students to lapses in professionalism.Conclusions: There is a broad range of consensus on the relevance of more than 40 forms of poor professionalism at the proto-professional undergraduate level and the appropriate responses that students should feel empowered to make to observed lapses. These data will give guidance in the development of e-learning programmes for UK students and to undergraduate Fitness to Practise Committees as they seek consistency in responding to lapses in professionalism by students and teachers at the undergraduate level.