["TESOL Quarterly, Volume 60, Issue 1, Page 349-378, March 2026. ", "\nAbstract\nThe current ethnographic case study traces a Chinese undergraduate student's investment in learning and socializing into specific disciplinary and professional discourses at a U.S. university and beyond. Drawing on Darvin and Norton's (2015) investment model, this study examines how his identity construction and negotiation were mediated by his exercise of agency, access to capital and resources, and ideologies within his situated contexts. Data collected from class observations and multiple interviews reveal that the focal participant, Xing, driven by his imagined identity as a cosmopolitan business professional, strategically mobilized various forms of capital and institutional resources to actively socialize himself into the disciplinary discourse community of finance and accounting. Nevertheless, his efforts were constrained by his positioning as a deficient English language learner during interactions with others. This positioning is rooted in the monolingual standard English ideologies. Although Xing employed strategic approaches to negotiate this position within academic contexts, these efforts did not necessarily signify empowerment. Instead, they risked perpetuating the linguistic hierarchies and power structures that disadvantaged Xing in the first place. The findings caution educators against an uncritical emphasis on learner agency without addressing the ideological forces that shape learners' choices. In addition, educators are encouraged to guide students to critically engage with the disciplinary discourse communities to prepare them to navigate future professional environments characterized by varied and sometimes conflicting language norms and practices.\n"]