Research spanning more than two decades points to the benefits of vigorous collegial communities, yet relatively little research examines specifically how professional communities supply intellectual, social and material resources for teacher learning and innovations in practice. This paper examines the theory-building potential of audio- and videotaped records of situated interaction among teachers in the course of everyday work. The paper employs a small segment of a larger data set to chronicle analytic dilemmas and opportunities and to introduce a scheme for theorizing about the nature and significance of professional community for teacher development and school reform.