Plagiarism is a broad and multidisciplinary field of study, and within second-language (L2) writing, research on the topic goes back to the mid-1980s. In this review article we first discuss the received view of plagiarism as a transgressive act and alternative understandings which have been presented in the L1 and L2 writing literature. We then survey and identify salient themes in the growing body of work relating to plagiarism, primarily from an L2 writing/applied linguistic perspective. These themes include terminological distinctions; views of the role of textual plagiarism in language learning and a writer's development; a concern with students’ and teachers’ sometimes differing understanding of plagiarism; and disciplinary differences in perceptions of plagiarism. We review research into the role of the electronic media in changing orientations toward plagiarism, the potential role of culture as a cause of plagiarism in the work of L2 writers, and pedagogical approaches to guiding students away from plagiarism. Methodological issues in researching plagiarism are surveyed, and the article concludes by suggesting directions for future research.