This study examines the values and practice in relation to assessment of a sample of 220 trainee teachers studying for a Postgraduate Certificate in Education, an initial teacher training and education (ITET) course, at the University of Cambridge, UK. The survey instrument was drawn from James and Pedder (2006), and was composed of questionnaire items that sought to elicit how trainees valued different classroom assessment practices, and the extent to which their own teaching complied with such values. The study draws additionally on the findings of James and Pedder (2006) to compare and contrast results with those for qualified teachers. Item and factor analyses revealed three dimensions that underpin trainees' classroom practice and values (promoting learning autonomy, performance orientation, making learning explicit). Values-practice gaps were greatest on promoting learning autonomy and performance orientation. Trainees valued practices associated with the former more than they implemented them in their teaching, while they implemented practices associated with the latter more than predicted by their values. Values-practice gaps suggested that trainees were constrained from implementing their values to a greater extent than qualified teachers, particularly with respect to these two factors. (Contains 9 tables.)