This article explores the construction of a bilingual professional identity in a bilingual creative-writing graduate program in southwest Texas by analyzing a classroom event and the participants' interpretation of it. In bilingual classrooms the resources available to construct professional identities include a large repertoire of linguistic practices and cultural frames. This context provides a space to explore how language, power, and identity are negotiated in bilingual settings. The data were analyzed from a social constructivist perspective using tools from Systemic Functional Linguistics (Halliday, 1994; Martin & White, 2005) and theme patterns. The paper demonstrates how 3 types of positioning--attitudinal, dialogic, and intertextual--contribute to the construction of various bilingual professional identities in the community and the idea that both Spanish and English are considered legitimate in the construction of disciplinary knowledge. The conclusions point to the importance of interpreting and explaining professional-identity construction as dynamic practices set in sociohistorical context. (Contains 3 tables and 6 footnotes.)