Teacher assessment literacy is a phrase that is often used but rarely defined. Yet understanding teacher assessment literacy is important in an international curriculum and assessment reform context that continues to challenge teachers' assessment practices. In this article situated examples of classroom assessment literacies are analysed using Bernstein's ("Pedagogy, symbolic control and identity: Theory, research and critique," Taylor and Francis, London, 1996; "Br J Sociol Educ" 20(2):157-173, 1999) theoretical tools of vertical and horizontal discourses, classification and framing. Drawing on a sociocultural view of learning, the authors define teacher assessment literacies as dynamic social practices which are context dependent and which involve teachers in articulating and negotiating classroom and cultural knowledges with one another and with learners, in the initiation, development and practice of assessment to achieve the learning goals of students. This conceptualisation of assessment literacy aims to make explicit some underpinning theoretical constructs of assessment literacy to inform dialogue and decision making for policy and practice to benefit student learning and achievement.