The study examined the role of action research in promoting critical reflective thinking among twenty preservice teachers engaged in a year-long middle level program. Data from collaborative discussions, final written documents, presentations, and follow-up surveys revealed that conducting action research (a) engaged them in inquiry into their own practice, (b) was a means to reflect upon and determine ways to change their teaching practices, and (c) promoted critical reflection in a collaborative learning environment. Results underscore the importance of preservice teachers critically reflecting to gain insights into teaching and student learning as they are engaged in action research. (Contains 2 tables.)