Assigning a fail grade, particularly when it results in the termination of a career goal, is a taboo and taken-for-granted aspect of an assessor's role. Hermeneutics provided the main framework for interpreting the subjective and objective experiences of both academic and fieldwork supervisors during this process. An incremental research design, using a principal and two supplementary methods was used to investigate the minutiae of assessing whether a student has achieved the required standard of competence. Focused interviews were conducted with 25 academic and 5 fieldwork supervisors to compare the perspective of staff with different roles, relationships and responsibilities. These were preceded by two questionnaire surveys with trained, experienced fieldwork supervisors. On the first survey 64% (n=72) ranked 'failing a student' as their most problematical responsibility. The second survey comprised immediate and follow-up evaluations of five 'failure workshops' attended by 101 supervisors. They highlighted the importance of an assessor's affective response, reinforced effective supervisory strategies and the professional obligation to act as a gatekeeper of future standards. The results revealed a diverse array of individual factors, institutional rituals and external pressures which seemed to facilitate or sabotage the quality of the process and outcome. These included an assessor's inexperience, the conflict in values and roles between therapist and educator; characteristics of the student particularly the pastoral relationship and stage of training; the valued impartiality of an external examiner or fieldwork organiser; and the threat to reputations and course viability if results provide the primary performance indicator. An understanding of the complex constellation of factors which may influence an assessor's ability and confidence to fairly judge both initial and ongoing competence is important for all 'caring' professions to ensure only safe practitioners are registered to work with vulnerable clients.