This article examines how primary school mentor teachers made their decisions regarding teacher candidates' practicum performance. The mentor teachers’ explanations for their decisions gave the authors access to their ‘cue utiltisation validities’ - how they used the cues they identified. Within the participant group some appeared to emphasise personal attribute dimensions, other professional practice dimensions; for others it was difficult to determine a preference. There was, however, evidence that the mentors did not emphasise one thing to the exclusion of the other cues with weaker cues being used to moderate their decisions. Overall, the judgment-making in this study was considered, careful and reasoned e and widely variable. There was also some evidence of internal dissensus for individual mentors, leading to confusion around assessment of TC practice.