In this study, we aim to understand the forces driving assessment for learning (AfL) in primary school teaching. By applying a case study design, including the two cases of Norway and Portugal and using mathematics teaching as an example, available policy documents and research reports are analysed to identify the differences and similarities that might explain the assessment practices previously observed in the two countries. Many similarities are found at the school and national levels. In particular, AfL is introduced as a national policy in both countries. Still, AfL practices are not common in primary mathematics classrooms in either country, although this is true for different reasons in each country. It is suggested that the assessment culture caused by national policies, such as curriculum reforms, national professional development projects and teacher autonomy, explains the similarities in the observed outcomes.