This paper reviews the background of and compares three particular approaches to reflective professional development, specifically as used by Far West Laboratory: case methods, the Peer Assisted Leadership process, in which peer partners observe each other, conduct reflective interviews, construct leadership models, and explore alternate ways to handle dilemmas they face as school leaders; and teacher action research. It further describes how theory, data, and discussion are intertwined in each approach; what forms of knowing and reasoning emerge; and how these processes unfold in several specific examples. A distinctive characteristic of the approaches, as compared to their reflective processes, is the emphasis on in-depth consideration of real world experience or the documentation and interpretation of specific situations, here labeled as a focus on data. Discussion is a process tool by which participants articulate and reconsider interpretations of experience and try out and adjust different theoretical frames. By focusing on data or experience, many different forms of knowing and learning become relevant and useful, including propositional knowledge, narrative knowledge, and reflection through action. Each case is reviewed in terms of story, theory, action, question form, data/research, agency, and complexity. Appendixes include four examples of teacher research cases and an annotated bibliography of reflective professional development model literature. (Contains 49 references.) (Author/NAV)