The focus of this article is on the ways in which an analysis of professional discourse within a school can contribute to a school's self-evaluation. The project included an opportunity sample of nine schools and involved members of the research team, senior management and teachers in each school working in collaborative partnership. A research journal was completed over a four-week period. The article concentrates on the second of two phases, professional discourse in the school, and it highlights the extent to which such data provide insight into characteristics of professional life in the school. The project methodology and its implementation are exemplified in a case study of one of the participating schools. In particular, the case study illustrates the potential of professional discourse analysis as a tool for improving a school's self-knowledge, for scaffolding reflection and for school improvement through focused and coherent action planning.