This qualitative case study examined the impact on five master teachers who engaged in teacher research as an alternative to the traditional evaluation process. The principal's learning was also chronicled through field notes. Data on each participant was collected through individual interviews, written reflections and research reports, and through final oral presentations before peers and administrators.;The researcher/principal blended theories of adult learning, quality professional development, and leadership to create a framework for the teacher research course as alternative evaluation. As a result of the experience, teachers became more efficacious collaborating with other professionals, capitalizing on collective wisdom. Hence, the collective learning of the group was greater than the more limited learning during the traditional evaluation process.;School leaders cannot assume differentiated evaluation via professional development will have a positive effect on practice. Instead, they must pay close attention to the conditions that maximize the learning of master teachers by (1) providing opportunities for reflection and refraining, (2) building a supportive culture of teamwork and collaboration, (3) capitalizing on the collective wisdom of the group, and (4) scaffolding for successful experiences that increase teacher efficacy.;The principal in this study reconciled the conflict between accountability and professional learning by concluding that accountability for the participants flowed from the learning rather than from the evaluator's more limited observation of teaching. It was established that the needs of master teachers differ from those of the novice, making a case for the creation of differentiated evaluation systems.;Finally, the researcher proposed expanding the mental model of principal as leader to include principal as teacher and teacher as leader. By viewing leadership through the lens of teacher, the principal has the potential to change the culture of schools to reduce isolation, create communities of professional learners, and elevate the status of teachers in order to have a greater impact on student achievement. |