In this paper the author presents a framework for understanding how improvement-oriented high school teachers' accounts of change experiences portray their evolving roles as change agents in school reform. The data on which this paper is based come from a one-year long in-depth study (doctoral thesis research project) in which the author set out to investigate how improvement-oriented teachers pursue important changes in the realm of classroom, school and community; how the teachers-initiated changes can be characterized; and how the teachers' roles evolve with their change practices. The researcher employed qualitative case study methodology, using in-depth interviews, classroom observations, post-observation discussion, and document analysis, as the main sources of data. The teachers whose change practices and values are depicted in this report recognize their roles in pedagogical, institutional and social change, and wherever possible, they try to engage in efforts to bring these changes about. Through the study the author recognizes an inherent link between teachers' endeavors aimed at bringing about fundamental change in the classroom and their efforts towards promoting institutional change in the schools and social change in the community.