Teacher inquiry, in which teachers study their own professional practice, is currently a popular form of experiential learning that is considered a powerful tool to bring about effective change in teaching and learning. Little empirical evidence, however, exists to explain precisely if and how this pedagogical methodology moves teachers toward transformation of practice. Using a grounded theory design, we examined twelve end of term graduate level learning portfolios and administered a survey to 336 in-service teachers enrolled in a two-year graduate diploma program in the Faculty of Education at Simon Fraser University, Canada. We found powerful evidence that our programs were highly impactful, with 94% of teachers reporting transformative learning within the second year of the program. Using portfolio data, we examined the process of the teacher transformations. Our findings revealed that teachers' abilities to interrogate their subjective-objective stance deepened their experiential learning. Using three case studies we exemplify how transformative pathways were formulated and conclude with a discussion of the implications of learning through experience, including the value of student-generated learning goals, continuous interfacing of theory and practice, seeing your "teaching" through the eyes of your students, colleagues or parents, and the power of living your research question in the context of your own classroom and school setting. We end the paper on a cautionary note pointing out the vulnerability of programs of this nature in an era of accountability, standardization, quality control, and risk management all of which eclipse approaches that focus on authentic practical problems and student generated solutions.