This study investigates how different stakeholders in Norway experienced a government-initiated, large-scale policy implementation programme on "Assessment for Learning" ("AfL"). Data were collected through 58 interviews with stakeholders in charge of the policy; Ministers of Education and members of the Directorate of Education and Training in Norway, and the main actors such as municipality leaders, teachers, school leaders and students. Successful implementation of AfL processes was found in municipalities where there were dialogue and trust between the municipality level, school leaders, teachers and students and where the programme was adapted to the local context. Implementation was challenged when the policy was interpreted as a way of controlling the schools. Despite the successful implementation in some municipalities, the programme did not have any effect upon students' learning outcome, as measured on national tests in reading and mathematics. The results are discussed in relation to how local assessment cultures with particular characteristics influence governing, accountability and trust.