Abstract This article presents an in-depth case study of a complex community of inquiry. In this community, teachers worked collaboratively to build from situated assessments of students'learning through reading to refine and monitor practices designed to enhance student learning in their subject-area classrooms. In this report, we present evidence to address three questions: (1) What did inquiry look like within this community?; (2) How was collaboration implicated in teachers' inquiry?; and (3) How was engagement in inquiry related to meaningful shifts in teachers' practice and learning? This research contributes by uncovering important links between teacher inquiry, collaboration, and educational change.