A professional development initiative in writing provided a context in which teachers could research their own knowledge about writing, writing assessment and writing instruction. Through close attention to student writing samples, and debate in ascertaining writing levels using the English Exemplars, teachers articulated growing confidence in their knowledge of language and the writing process. This was reflected in an increased confidence in, and ability to articulate, beliefs about writing instruction. The moderation process for ascribing levels to the student samples took place within professional learning communities. The paper identifies some problems in establishing these as productive and positive contexts for teachers as researchers.