Using a single case study design, this article describes the work of a participant researcher to assist a group of five high school teacher practitioners in reflecting on their teaching practices. Participants in this study attempted to apply action research to better understand the impact of their teaching approach (i.e., primarily lecture) on student learning as well as on their own styles of teaching. Work with these teachers was part of a larger effort to improve overall instructional quality in the school in the areas of teaching, curriculum professional development, and supervision. The article describes efforts of the participant researcher to create opportunities for teachers to apply action research to reflect on teaching practices. After briefly reviewing the literature on instructional change and action research, findings are presented on the manner which study participants reacted to applying action research to reflect on teaching practices as well as the degree to which it transformed their teaching. The article ends with a reflection on the challenges this school faced transforming instructional practices along with several lessons learned from the study.