This article reports on a mixed-methods study of Chinese university students' knowledge of and attitudes toward plagiarism in English academic writing. A sample of 270 undergraduates from two Chinese universities rated three short English passages under different conditions, provided open-ended responses to justify their ratings, and completed a written questionnaire. The rating tasks were designed to determine their ability to recognize two forms of intertextuality (i.e., unacknowledged copying and paraphrasing) generally regarded as plagiarism in Anglo-American academia. The questionnaire was administered to collect self-appraisals of competence in source use and to assess declarative knowledge of intertextual practices that match typical Anglo-American definitions of blatant and subtle plagiarism. Qualitative and quantitative analyses revealed that a minority of the students recognized the two forms of plagiarism and generally took a punitive attitude toward the detected cases of plagiarism. Further quantitative analyses found that discipline, self-reported competence in referencing, and knowledge of subtle plagiarism were consistently significant predictors of successful plagiarism detection. These findings raise questions about some culturally based interpretations of plagiarism and point to the need to take a nuanced approach to plagiarism in L2 writing. (Contains 6 tables.)