Using critical constructivism as the theoretical lens, the teacher educator-researcher used practitioner research to systematically examine the experience of PreK-12 teachers in his district-based teacher research professional development course, while also examining his development as a teacher educator. The results of this study showed that, as the teachers made progress toward becoming teacher-researchers, they expressed being empowered by the teacher research process. Moreover, they showed a growing critical awareness in their work, while the teacher educator was challenged to re-examine his conceptions of teacher research. Finally, the teachers faced several important barriers in adopting an inquiry stance in their practice. This research generates both local and global knowledge about teacher research as a form of in-service teacher education.