In second-language writing, assessment has traditionally focused on the written products and how well (or badly) students perform in writing. Teachers dominate the assessment process as testers, while students remain passive testees. Assessment is something teachers "do to" rather than '"with" students, mainly for administrative and reporting purposes (i.e. summative). Such assessment, being more retrospective than prospective, holds little value for teaching and learning. In recent years, with a major paradigm shift in assessment and evaluation in English language teaching, writing assessment informed primarily by a product and summative orientation, is considered increasingly inadequate. Such assessment, which focuses on measurement--i.e. marking, monitoring and checking, fails to capture the formative potential of assessment for promoting learning. A formative approach to assessment, on the other hand, focuses more on inquiry--i.e. discovering, diagnosing and understanding, as well as the opportunities assessment provides for improving teaching and learning. To harness the potential of formative assessment in the writing classroom, it is axiomatic that classroom assessment practices be geared towards maximizing student learning. This provides the impetus for my study, which investigates an EFL teacher's attempt to implement formative assessment in her writing classroom and its impact on her classroom practice and students' beliefs and attitudes to writing.