Nontraditional students often have different learning styles and individual needs compared to their younger classmates. They are generally highly motivated and have a more fully developed set of life skills as well. In Japan, as the number of nontraditional students increases, one concern that needs to be addressed involves the learning conditions language teachers create for increasingly mixed classes of traditional and nontraditional students. This paper demonstrates how classroom discourse analysis, as a form of teacher research, can address this concern. By studying the patterns of interaction with and between students, a teacher can gain a better understanding of how nontraditional students are positioned in classroom contexts and how this positioning may afford or deny opportunities for learning. First, I discuss classroom discourse analysis and offer a few practical suggestions on how teachers can get started researching the patterns of interaction in their own classrooms. Then, I present an example of my own teacher research on classroom interaction from an oral communication class. The example illustrates how a classroom interaction between a nontraditional student and teacher fails to affirm the L2 identity a nontraditional student fashions in the conversation.