This article focuses on the implementation of the vision of formative assessment advocated in the 2003 Learning Assessment Policy in Quebec. It reports on the partial results of research aimed at understanding how secondary school teachers' formative assessment practices are carried out and what challenges are encountered. The snowball method was used to select a sample of ten teachers based on the criterion of seniority in the profession, namely having started teaching before the implementation of this policy. The results show a variety of challenges related to the practice of the formative assessment policy.