Although contemporary second language learning scholars assert that teacher management of learner contributions in classroom interaction is key to promoting learning opportunities, research has yet to make explicit teachers' real-time management practices. Studies on classroom interaction have illuminated how learner contributions are elicited via questions and addressed via assessment and mediation. Still, our understanding of how such management is done in the details of classroom interaction, i.e., how teachers manage learner contributions as they emerge "in situ," remains unclear. Concurrently, language teacher cognition research focuses on the effects of teacher beliefs, knowledge, previous experience, and expertise on classroom practices, albeit often using data stemming from teachers' perceptions of their practices rather than the manifestation of these factors in actual classroom interactions. In bringing these fields together, the current study examines one expert teacher's management of learner contributions during whole-group interactions as they emerge "in situ" and the reasons behind such management as reported by the teacher. A mixture of conversation analytic (CA) and ethnographic data methods is utilized. The data come from an adult English as a Second Language (ESL) community program and include one pre-semester semi-structured interview with the teacher, 26 hours of video-recorded classroom interactions transcribed and analyzed following CA methods, and five stimulated recall sessions with the teacher regarding the CA findings. The analysis showcases a systematicity to the teacher's management of learner contributions, as specific discursive practices are deployed to manage learners' (possibly) correct responses to teacher initiations, their problematic responses to teacher initiations, and their initiatives. At the crux of such management is her focus on what learners "can" do as opposed to what they cannot, her treatment of learners as partners in a joint inquiry that underscores exploration, and her simultaneous consideration of a constellation of factors in her decision-making. The findings of this study not only contribute to the literature of classroom interaction and language teacher cognition but also iterate the strengths of bridging conversation analytic and ethnographic methods when examining language teacher practices. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]