Background The extent to which clinical competency development is assessed throughout postgraduate training programmes in professional psychology in Australian universities is variable, with significant differences in assessment philosophies and methodologies across academic institutions, and between clinical and field supervisors. Few competency assessment tools exist, and those that do have demonstrated limited psychometric support to date. This study reports the results of a preliminary analysis of a competence assessment tool developed for use within cognitive‐behaviourally oriented postgraduate training programmes of clinical and forensic psychology. Methods A working party of academics identified core competencies being taught within the programmes and articulated behavioural descriptions of each competency, graded across skill levels. Participants (n = 43) were students enrolled in postgraduate training programmes of clinical and forensic psychology participating in a 1 day per week, year‐long placement within a university‐based psychology clinic. Students were assessed utilising the competence assessment tool at a point midway through their placement and again at the conclusion of the placement. Result Preliminary analyses demonstrated that the Clinical Skills Assessment Tool is a psychometrically sound assessment instrument. Conclusion The development of a clinical competence assessment tool for use within postgraduate training programmes of clinical and forensic psychology supports the assertion that such programmes enhance the competencies they are designed to develop.