This paper sets out to (a) Theorize teacher identity as fluid, dynamic, interactionally emergent in situ, (b) Operationalize a dialogic narrative approach for the study of teacher identity on these terms, and (c) Account for the locally unfolding process of teacher identity, over short periods of time, in relation to curricular content. It pursues the inquiry through multi-layered small story analysis of a narrative, “My Worst Mistake,” told by a veteran English language arts teacher in the Midwestern United States.