Transforming Writing is a two-year action research project which aims to develop a model for the teaching and learning of writing that more fully incorporates a focus on embedded formative assessment. In the first year of the project, the 12 participating schools developed a model of writing underpinned by Talk for Writing, an approach developed by Pie Corbett and Julia Strong. This interim report evaluates to what extent the model of writing developed by the teachers during the first year of research impacts on children's writing in terms of attainment, confidence and engagement. The evidence so far suggests that the focused use of formative assessment by teachers with children and by children with peers can make a major difference to children's writing progress in terms of attainment, engagement and confidence. This report identifies some of the successful classroom approaches to embedded formative assessment in writing teachers developed in the first year of the research project. The report suggests that during Transforming Writing research, teachers became evaluators and activators in the sense that Hattie (2012) proposes. Teacher interviews and reflections reveal that teachers were evaluating the effect their teaching had on the children's learning then using the powerful feedback that formative assessment provided to rapidly respond and adjust teaching of writing. Teachers saw their key role as evaluating their effect on children's learning of writing and then responding by implementing deliberate and focused interventions. Appended are: (1) Glossary; (2) Talk for Writing--what is it?; and (3) Table to show connections between the developing practice and findings of participating teachers on the Transforming Writing project in Phase 1 of the research project and the research of John Hattie. (Contains 21 figures and 14 footnotes.) [Funding for this paper was provided by Esmee Fairbairn Foundation.]