This article introduces the construct of teacher noticing, situates it in research on second language teacher cognition, and considers its implications for research on second language teacher training, acknowledging socio-cognitive perspectives on language learning and teaching. We then present a mixed-methods observational study that utilized quantitative and qualitative approaches to study novice teacher noticing in the context of teaching demonstrations carried out as part of eight participants' undergraduate course requirements. Teacher noticing was defined as awareness of features of second language classroom interaction that may influence student learning. The goals of the study were to: (1) assess our approach to studying teacher noticing, (2) examine the interactional contexts in which teacher noticing occurs, and (3) identify themes in novice teacher noticing. The results indicated that the stimulated recall methodology used was, not surprisingly, sensitive to the time delay between teaching demonstrations and recall interviews. Nonetheless, all participants reported noticing. Teacher noticing occurred primarily when the participants were teaching to the whole class and tended to involve the difference between plans vs. reality, noticing as a trigger for action, and individual learner contributions. The discussion weighs the strengths and limitations of this study and explains how a focus on the significance that teachers place on classroom interactions they become aware of during lessons may benefit research on language teacher education.