This article discusses how the underlying assumptions and practices of teacher research position it as a distinct form of educational inquiry, and identifies qualitative methodology as a central influence on the work. A discussion of some of the common conceptualizations and processes of PK-12 teacher research, the complex yet continually changing educational knowledge it represents, validity and ethical issues, and its political nature, framed by accounts of teacher researchers who work with today's diverse student populations, illustrate how a qualitative stance reflects and informs this profoundly contextual form of pedagogical inquiry. (Contains 2 notes.)