abstract: Teacher learning in the workplace is situated within a complex context involving the individual and multiple aspects of an educational organization. The present action research study uses a socio-constructionist inquiry lens to further research the local and multifaceted nature of professional learning in schools. The goal is to re-conceptualize professional development away from reductionist approaches that assume teacher practice can be isolated, packaged, and directly transferable into the classroom. The present study examines how lesson study can structure interdisciplinary professional learning to address the current gap in the literature regarding professional development of secondary specialty teachers. Five teachers participated in two lesson study cycles for a period of 13-weeks. This study focused on how teachers co-construct pedagogical knowledge and the extent to which they make changes to their practice. Using a sequential mixed methods research design, this study collected qualitative and quantitative data in three phases. In the initial phase, participants completed a demographical survey and shared a digital ethnography of their philosophy of teaching. Phase two consisted of video recordings for two lesson study cycles. Phase three involved a second survey and semi-structured interviews. Classroom observations were conducted during the first and last phase of the study. All qualitative data was analyzed inductively using open and thematic coding. Cross-case analysis was employed at the analysis stage to integrate data tools for the purpose of complementarity. Results suggest lesson study was an effective, job-embedded model that supports active and continuous professional development that is sustained and transferrable to the classroom. The type of disposition reported and displayed by teachers changed positively over time having transformational effects in the depth of relationships among teachers, increasing co-creation of pedagogical knowledge, and increasing reflectiveness. Teachers' level of openness to learning related to higher levels of effective practices implemented during lessons. Further research is needed to examine the ways in which teacher disposition influences professional learning when secondary specialty teachers engage in lesson study. / Dissertation/Thesis / Ed.D. Leadership and Innovation 2014