Background: The latest curriculum reform in Norway is one example of an education reform with a highly emphasised assessment for learning (AfL) agenda. Acknowledging that there is a lack of empirical research on AfL in physical education (PE), and that AfL potentially can have an important role to play in development of PE pedagogy, this paper set out to examine the extent to which the emphasis on AfL from educational authorities has led to change in assessment practice in PE. Purpose and research question: The purpose of this paper is to examine the implementation of AfL in PE at upper secondary level in Norway, and discuss possible implications. More specifically we ask "How do students' and teachers' perspectives of assessment practices in PE reflect AfL key principles?" Methods: A mixed-method design has been applied in this study. Quantitative data, collected through a questionnaire answered by 1486 students from six upper secondary schools (15-19 years), were combined and compared with qualitative data from focus groups of a total of 23 PE teachers at the same schools. Data were analysed in relation to four key principles of AfL. Findings: For the majority of the students in the study, their reports of assessment practice in PE did not reflect the four key principles of AfL. This result was supported by the fact that their PE teachers conveyed very varied understandings and enactments of AfL. The study revealed some difference between teacher and student perspectives regarding AfL key principles, in particular regarding feedback that moves learners forward. Conclusions: The study demonstrates limited implementation of AfL principles in PE and we conclude that the educational authorities' emphasis of AfL has not proven productive in PE. However, most of the teachers acknowledged the need to change teaching and assessment practices in PE, and all schools in the study are observed to be in an area of changing assessment. Considering the findings on different AfL key principles, this study highlights engaging student more directly in assessment processes as an important development area.