Teachers’ knowledge is personal, context-rich, and elusive. This chapter approaches the issue of researching teaching by demonstrating the power of critical dialogue in naming and transforming teachers’ professional knowledge. In this instance, the dialogue is made possible by the authors’ shared commitment to probing the importance of pedagogy and experience in facilitating learning. Tom is an experienced teacher educator seeking the best ways to identify and encourage the learning of science teacher candidates in a program based on early extended experience; Shawn is a teacher candidate coming to terms with his first extended teaching assignment and his preservice education courses. Each is helping the other identify and interpret his professional knowledge as a teacher by reading and commenting on e-mail accounts of teaching-learning experiences. Sharing our personal experiences of teaching drives the process of naming our professional knowledge as teachers. By grounding our analysis in experiences of teaching and critical dialogue about teaching, we demonstrate how we come to understand our knowledge and our ongoing efforts to extend, refine and consolidate that knowledge.