||Research that has examined how L2 writers write from sources and the extent to which these source-based text;s differ from text;s produced by L1 writers suggests that L2 writers copy more extensively and attribute information to original sources less frequently than L1 writers (e.g., Keck, 2006). This dissertation study set out to add to the existing body of literature on text;ual borrowing in undergraduate L2 writers with the additional goal of examining the extent to which these writers‘ text;ual borrowing is influenced by instruction on avoiding plagiarism. The study employed qualitative methodology and drew upon multiple data sources. Additionally, unlike much of the existing research on L2 writers‘ text;ual borrowing, this study examined three L2 writers‘ text;ual borrowing in the context; of authentic source-based assignments produced in an ESL writing class and mainstream courses. The findings showed that the three L2 writers in the study were able to avoid blatant plagiarism by implementing basic text;ual borrowing strategies, such as paraphrasing by substituting original words with synonyms. However, they continued to have difficulties with more nuanced aspects of source use, such as transparency and cohesion in attribution, integration of source-based material with their own voice, source selection and organization, and use of effective reading and writing strategies. With respect to the observed instruction, the study uncovered several central themes: the instructor 1) tended to focus on the punitive consequences of plagiarism (although her perspective shifted toward the end of the course), 2) frequently emphasized concepts of credibility and blame as main reasons for responsible text;ual borrowing, and 3) simplified instruction on text;ual borrowing to rephrasing of others‘ words and changing structure. These findings highlight the mismatch between the complex difficulties that undergraduate L2 writers have with text;ual borrowing on one hand and the simplified instruction that ignores these difficulties on the other. I discuss this uncovered disparity in the realm of L2 writing teacher preparation and professional training for faculty across the curriculum, arguing for increased institutional support. I also outline a framework for providing such instructional support, which includes linguistic, text;ual, cognitive, metacognitive, and social support.