Among scholars of applied linguistics and composition studies, the notion of academic literacy has generated discussions regarding L2 students' intellectual growth and academic performance in the college context. Several studies provide a detailed account of how students adapt their literacy practices in response to their perceived needs for task completion; however, as the notion of academic literacy has gradually been linked to concerns of disciplinary enculturation, a situated process of becoming involved in disciplinary discourse, there has been a call for attention to the disciplinary discourse communities into which students are initiated through literacy tasks. Although some previous studies have forged early linkages and integrated disciplinary discourse into the notion of academic literacy, the empirical data comes from graduate students (Casanave, 2002; Prior, 1998) or L1 students (Hass, 1994; Herrington, 1985; Sternglass, 1997). The study reported in this dissertation, however, investigates the situated and enculturating literacy practices of L2 students in undergraduate settings. Also, as compared to previous studies that describe the literacy strategies in or students' views of disciplinary discourse, the present study attempts to schematize the connection between literacy practice and disciplinary enculturation, drawing on the notion of genre and its framework. This study has a clear focus of analysis by discussing the literacy practice of two L2 students as they engage in genres, mostly written work, in class, herein referred to as genre practice or genre-mediated literacy practice. This study follows the L2 students' learning throughout their undergraduate college experience, providing an analysis of their genre practice across disciplines from their first year to graduation, and at the same time tracing the factors that contextualize their genre practice, such as previous genre encounters, class work, writing assignment guidelines, cultural norms, individualized perceptions of disciplinary expectations, etc. Through careful textual analysis and interviews, this study focuses on the L2 students' developing academic literacy as mediated by discipline-specific genre practice in three different learning contexts: writing in general education courses, writing in business writing courses, and writing in courses in their majors. The results of the study show that both students' genre practices varied, depending on how genre was cued, interpreted, and performed, by social affordances such as lectures, class readings, class discussions, and interactions with peers and instructors. The study shows the students' genre practice taking shape in the way they were situated in disciplinary discourse, while at the same time their understanding of disciplinary discourse was mediated by their engagement in genre. In addition, by looking at the students' genre practice in four different knowledge dimensions—formal, rhetorical, procedural, and subject matter (see Tardy, 2009)—this study documents a detailed process of constructing discipline-specific literacy. Despite its context-dependent, individualized positioning in disciplinary discourse, this study captures a series of patterns of literacy practice cutting across the two L2 students' approach to genre and highlights the issues inherent in classroom-based instructional settings. The theoretical and pedagogical implications of this study suggest the need to reexamine the role of writing for discipline-specific literacy, both to enhance college writing instruction and to advocate for writing across the curriculum.