This article reports on a collaborative study involving ESL teachers in an Australian English Language Centre as they work through some of their concerns about reliability and validity in their assessment practices. The focus of this article is on how teachers work with the Curriculum Standards Framework (CSF) as an assessment tool. The discussion focuses on issues relating to the limitations of the CSF and the way in which teachers engage with the CSF to produce a meaningful and accurate assessment reflective of their students' progress. The teachers' stories highlight how state-mandated assessment policies are translated into teacher assessment carried out in local educational contexts. Harre's positioning theory (1999) is used as the framework for interpreting the epistemological authority of the teachers within the assessment exigencies of the education system.