Using a case study design and ethnographic methods, this research investigated the interactions of a group of high school mathematics teachers who collaborated daily on issues related to curricular and pedagogical reforms. The members of the collaboration team implemented these reforms with the goal of supporting all students' learning of 1st-year college preparatory mathematics. This study used conceptual tools from frame analysis (E. Goffman, 1974) alongside an analysis of teacher participation patterns to understand teacher learning within a community of practice (E. Wenger, 1998). This analysis documented development within the teacher community through teachers increasing orientation to classroom-based interventions for struggling students alongside more collegial participation patterns, contributing an empirical example of teacher learning within a community of practice.