Mathematics teachers develop understandings about instruction across multiple settings, such as classrooms, workshops, and professional learning communities. When teacher teams collaborate, their prior teaching and learning experiences meaningfully inform their sensemaking. However, current research does not explicitly link teacher conversations and these multiple settings for learning. In this study, we seek to understand secondary mathematics teachers' collaborative learning in schools as part of broader teacher learning ecologies. Using discourse analysis and a comparative case study design, we examine how two teacher teams' conversations recruit external conceptual resources to support the development of their collective pedagogical judgment. In particular, these external resources offered the teams rich representations of practice and productive framings of teaching problems. [For the complete proceedings, see ED629884.]