Doctoral students were randomly assigned to a five-week (30-h) faculty-led writing workshop intervention, either preceded by a five-week (waiting list) control phase or followed by a five-week maintenance phase. In the workshop, students wrote together, received instruction in genres of academic writing (literature reviews, scientific articles, funding proposals, and presentations), and exchanged feedback on drafts. As a result of the workshop students enjoyed writing more, found writing easier, and gained confidence in themselves as academic writers. They felt able to write productively in shorter blocks of time, and they engaged in more short-term, medium-term, and long-term planning of their research. The intervention also caused participants to pause more frequently for reflection or positive thinking and to generate more new writing. Effects were maintained in a peer-led writing maintenance group for at least five weeks after the intervention ended. This is the first randomized controlled trial of a doctoral-level writing intervention to date and has the potential to support doctoral training in academic and scientific writing across the Social Sciences, Education, and the Humanities.