The purpose of this study was to investigate socio-cultural factors underpinning curriculum change by examining teacher beliefs in the context of professional development. Scottish teachers in the study were participating in policy implementation based on formative assessment. Teachers were selected who were positive about the formative assessment initiative, so as to examine the inter-relationships amongst beliefs, policy, and practices when teachers intended to implement curriculum innovation. The aims of the study were to investigate: (a) the nature of teachers' beliefs about teaching, learning, and the professional development programme; (b) how those beliefs influenced the teachers' mediation of reform policy in their own classrooms; and (c) points of resonance or tension between teacher's beliefs and the council's philosophy towards and management of policy implementation. A qualitative interpretive cross-case study approach was used with five participant teachers from different secondary subject areas. Results suggested that the unique stance of district administrators to give teachers the opportunity to create their own reform methods, a "bottom up" mode of implementation, appeared to be a significant factor in promoting the reform policy. (Contains 1 note, 1 table, and 1 figure.)