Incorporating video case study of mathematics teaching into professional development (PD) can provide opportunities for teachers to develop new ways of seeing teaching and learning and inform efforts to enact new instructional practices. However, more research is needed to understand how such PD can foster sustained teacher learning about high-quality instruction and materials. In this paper, we share the evolution of our analytic method that aims to reveal how secondary mathematics teachers learn while collectively analyzing video of mathematics teaching. We found that conceptualizing this PD within a community of practice, along with applying analytic tools from frame analysis and professional noticing, helped us recognize and describe the process of teacher learning in this setting. We plan to apply our analytic method to our full dataset to better understand how teacher learning in this context is happening over time. [For the complete proceedings, see ED629884.]