Context: At present, competency-based, outcome-focused training is gradually replacing more traditional master-apprentice teaching in postgraduate training. This change requires a different approach to the assessment of clinical competence, especially given the decisions that must be made about the level of independence allowed to trainees. Methods: this study was set within postgraduate obstetrics and gynaecology training in the Netherlands. We carried out seven focus group discussions, four with postgraduate trainees from four training programmes and three with supervisors from three training programmes. During these discussions, we explored current opinions of supervisors and trainees about how to determine when a trainee is competent to perform a clinical procedure and the role of formal assessment in this process. Results: When the focus group recordings were transcribed, coded and discussed, two higher-order themes emerged: factors that determine the level of competence of a trainee in a clinical procedure, and factors that determine the level of independence granted to a trainee or acceptable to a trainee. Conclusions: From our study, it is evident that both determining the level of competence of a trainee for a certain professional activity and making decisions about the degree of independence entrusted to a trainee are complex, multi-factorial processes, which are not always transparent. Furthermore, competence achieved in a certain clinical procedure does not automatically translate into more independent practice. We discuss the implications of our findings for the assessment of clinical competence and provide suggestions for a transparent assessment structure with explicit attention to progressive independence. © Blackwell Publishing Ltd 2009.