This study examines the nature of the initial implementation of a new multicultural sociology curriculum by eight teachers in the 11th- and 12th-grades of seven Israeli high schools. The study examined: (1) the extent and ways in which teachers reframe their theories of action as they learn to implement the new curriculum; (2) the factors that fostered and hindered reframing; and (3) the way teachers' constructs shaped the new curriculum. A variety of qualitative methods were used to gather data about the teachers' theories of action including focus group discussions, individual interviews, and classroom observation. Findings indicate that during the course of the implementation process half of the teachers made considerable modification of their theories of action. Teachers changed core assumptions about learning, teaching strategies, and role relations; however, they reframed their theories in very different ways. Factors found to foster reframing were staff development meetings, involvement in curriculum development, feedback processes, the quality of the curriculum materials, and the teacher's ability to take the stance of an inquirer. Factors hindering implementation and changes in theories of action were the attitudes, skills, professional commitments and workloads of teachers, and institutional norms. Teachers' experiences with implementing the curriculum led to significant changes in the shape, but not the basic principles and goals of the curriculum. (EH)