Assessment decision making is a highly contextual phenomenon. In this paper, we explore this topic in vocational education and training (VET). Thirty-eight teachers from five Norwegian upper secondary schools were interviewed before and after an 18-month research–practice partnership. To understand assessment decision making in VET, we draw on two bodies of knowledge: (a) research on teachers' decision making in assessment and (b) conceptualizations of teachers' professional capital. Four main findings emerged from the analysis: three assessment-related dilemmas and one professional capital-related dilemma. We then discuss how these aspects of practice affect assessment decision making and the implications for developing VET teachers' decisional capital.