This article is based on a study of what characterizes a teachers’ professional development in relation to assessment for learning. The study is a qualitative study of nine primary and lower-secondary schoolteachers, and follows how they systematically developed their competence on assessment for learning over a period of two years. The data consists of video-recorded classroom observations and of both oral and written teacher reflections captured throughout the two-year period. 

The results show that the teachers’ development went through three distinct phases, from an instrumental approach to a more theoretical and reflective approach to assessment for learning. The article concludes that development of practice takes time and that sustainable development is affected by both actions and theoretical reflections. 

Keywords: vurdering, lærere, profesjonskompetanse, skoleutvikling, kvalitativ studie