Although inequities are rooted across the educational ecosystem, access to high-quality learning represents a salient inroad for improving marginalized students' educational experiences. However, preparing teachers to enact equity-centered pedagogy--that which renders high-quality learning accessible to all students--remains a multidimensional problem with a dearth of empirically supported solutions. Given special educators' central role in supporting marginalized students' learning, ensuring that special educator preparation supports the development of an equity-centered practice is of particular importance. Therefore, this study examines Teacher Study Groups (TSGs) as a model for building preservice special educators' practice and, in doing so, examines the underlying processes of preservice learning that result in instructional improvements. My conceptual framework articulated communities of practice theory with empirical research on teacher learning and the conception of "critically inclusive" pedagogy, which cross-pollinates access- (i.e., Universal Design for Learning) and asset-based (e.g., culturally sustaining pedagogy) paradigms. To understand the underlying processes that preservice teachers' traverse as they build capacity in critically inclusive practices, I studied preservice teachers' participation in a course-embedded TSG. Through a convergent mixed methods design, I examined 60 preservice teachers' instructional quality prior to and following participation, along with their knowledge, attitudes, and knowledge calibration, as well as teaching artifacts and reflections shared during weekly sessions. In alignment with a convergent approach, I first analyzed quantitative and qualitative data separately, and I then integrated data through a joint display analysis to generate meta-inferences. Results indicated that participants significantly improved practice and foregrounded salient participatory experiences that hindered and facilitated participants' professional growth. I conclude with a discussion of implications for equity-centered teacher preparation. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]