Background/Context: Schools and districts are increasingly emphasizing evidence-based decision making as a means for improving teaching and learning. In response, professional development efforts have shifted toward situated, sustained activities that involve groups of teachers in reflective inquiry about student learning data, instructional practices, and curricular goals. Although strong evidence exists regarding the benefits of looking at student work, there is little research that investigates how teachers might work together to attain these benefits. Classroom teachers often lack the necessary skills and supports to enact data-based inquiry in a manner that informs and influences classroom practices. Purpose/Objective/Research Question/Focus of Study: In response to a need for specific frameworks to support teachers' collaborative interactions around student learning data, we have developed a conceptual framework for describing and characterizing key influences on teachers' actions and interactions. The purpose of this article is to fully describe the two dimensions that constitute the framework, illustrate them with examples from multiple cases, and discuss potential implications of the framework on research and practice. Population/Participants/Subjects: This framework was developed from multiyear case analyses of seven professional learning communities (PLCs). The teachers in these PLCs were secondary science and mathematics teachers who were supported by a 3-year professional development project. Research Design: We began to derive this conceptual framework using constant comparison in the development of semiannual case studies. Preliminary results and hypotheses on the specific ways in which teacher groups were interacting as they worked with student learning data led to the need to better conceptualize what was occurring. Building on others' work related to stance, we used grounded theory methods to construct and refine this framework. Findings/Results: A detailed framework and examples are provided regarding collaborative teacher inquiry groups' inquiry stance along two dimensions: (1) their epistemological stance toward student learning data, and (2) the nature of their dialogue when using these data in their inquiry process. The first dimension is delineated by four descriptive categories ranging from an improving to a proving stance; the second dimension ranges from sustained negotiation to no negotiation. Conclusions/Recommendations: This analysis of inquiry stance in a collaborative group is valuable in providing a detailed tool for empirical analyses of collaborative teacher development in the context of working with student learning data. Additionally, it provides practical support for facilitators and school leaders by characterizing fundamental and often hidden influences on PLC processes and outcomes.