There is general agreement in the literature that international students are more likely to plagiarise compared to their native speaker peers and, in many instances, plagiarism is unintentional. In this article we describe the effectiveness of an academic writing development programme embedded into a Biological Sciences Taught Masters course designed to reduce unintentional plagiarism amongst international students in the cohort. We compared plagiarism rates in the years before and after the implementation of the writing intervention. In addition, we analysed data from a high response rate questionnaire (87.8%: class of 90 students) designed to evaluate students' perceptions of the usefulness of the writing development programme and to elicit information about their prior educational experiences which might relate to plagiarism. Our combined quantitative and qualitative data show that an early pedagogical response reduced plagiarism levels amongst international students. However, the UK and international students in the same cohort reported markedly different responses to the writing programme. We therefore suggest that, if international students are provided with an initial opportunity to practise academic writing and receive feedback, they are more likely to be successful when writing coursework assignments later on. However, any initial writing development programme should be adapted to accommodate the differing needs of the UK and international students within the cohort.