This article focuses on assessment processes in the school subject of physical education (PE). Inspired by Torrance, the overarching research question is: 'What might assessment involve if it focuses on the development and identification of collective understanding, collaboratively produced through educational experiences?' The purpose of the study is to illustrate what characterises transformative assessment and show how it can be addressed in PE practice. A combination of group interviews with teachers, lesson observations and individual interviews with students and teachers was used to gather the empirical material. The analysis was based on three aspects of transformative assessment: responsibilisation; subjectification; and collaboration. Three empirical illustrations show what transformative assessment might involve in relation to learning tasks such as: the training log; the group choreography; and the case of exercise physiology. The views presented in this article contribute to the knowledge about the field in the following ways. First, the illustrations show that the 'whats', 'hows', 'whoms' and 'whys' in the assessment practice are often negotiable, which prevents a simplified understanding of the four aspects of assessment literacy: comprehension; application; interpretation; and critical engagement. Second, the notion of transformative assessment could hinder a reductive use of assessment for learning and promote collaborative learning and social justice in today's heterogeneous PE practices.