Based on a long-term research program by leading scholars, this is the first book to examine the language used by domestic and international students in first-year writing classrooms in the US. It emphasizes language choices by student writers as being informed not only by language background but also by other situational factors that influence language variation, such as the genre of the assignment, rather than employing the “overuse/underuse” paradigm. It also uses cutting-edge methodologies from corpus linguistics, including longitudinal analysis of texts across two to three semesters of writing-intensive coursework, and the use of multivariate statistics such as multidimensional analysis and cluster analysis. First-year writing is a required course for undergraduate students in the US, meaning this book fills an important gap in both research and pedagogy. It is essential reading for students and researchers of applied linguistics, writing studies, and rhetoric and composition focusing on quantitative research on student writing.