What Is It "Writing For Pleasure" Teachers Do That Makes The Difference? was a one year research project which investigated how Writing For Pleasure teachers achieve writing teaching which is highly effective (greater than average progress) and also affective (pertaining to positive dispositions and feelings). This research comes at a time where we are seeing profound underachievement in writing coupled with an increase in young people's indifference or dislike for writing. The principal purpose of this research was to identify and describe the kind of writing teaching which constitutes a Writing For Pleasure pedagogy. It was a requirement that the practices of the teachers participating in the research be based on what studies tell us are the most effective writing teaching, associated with high levels of pupil motivation, self-efficacy, agency, self-regulation, volition, writer-identity and pleasure in writing. Teachers were also required to provide evidence of exceptional or above expected academic progress among their pupils. The research investigated the principles employed by the most effective teachers of writing and linked them to the affective domains of Writing For Pleasure. The study employed a mixed method design. It required a combination of quantitative and qualitative data to be gathered. This included empirical data from participant observations, teacher and pupil interviews, viewing pupil assessment data and pupil questionnaires. From a rich literature review, an audit was generated which named fourteen interrelated principles, and their associated practices, which are strongly associated with high levels of student achievement and pleasure in writing. Findings showed that teachers who teach the principles of Writing For Pleasure at a high level of proficiency have classes who feel the greatest enjoyment and satisfaction in writing and in being a writer. Writing For Pleasure teachers attend to self-efficacy, agency and self-regulation in rich combination. Some principles of Writing For Pleasure were not observed at a high level of proficiency by the teachers as a whole data set and so need to be further investigated. The affective domains of motivation and writer-identity were not realised adequately by the pupils as a whole data set and so need to be further investigated. Finally, a Writing For Pleasure pedagogy is a highly effective pedagogy. [Co-published with The Goldsmiths' Company and The University of Sussex. The Goldsmiths' Company also provided funding for the project.]