In this essay, we consider four approaches to research on teacher knowledge: the scholarship of teaching, action research and teacher research, narrative inquiry, and critical-cultural teacher research. Similarities and differences among these four approaches are highlighted. The most salient difference lies in the way each approach identifies different discourses as sources of distortion in teacher knowledge research. Although some divergence within a field of study can be a valuable source of debate and dialogue, we believe the differences identified here risk dividing the field of teacher knowledge research in unproductive ways. What is needed, we propose, is a semiotic theory that acknowledges the way teacher knowledge is irreducibly mediated by multiple discourses while preserving a commitment to the idea that individual teachers' experiences can be a source of novel and useful knowledge. We examine two semiotic theories--French poststructuralism and Charles Sanders Peirce's pragmatic semiotics--and critically assess how they might facilitate more constructive dialogue among differing conceptions of teachers knowledge research.