This article examines a study on how preservice teachers enhance their understanding of theory and research in second language learning through an action research project that took place in a TESOL (Teachers of English to Speakers of Other Languages) education course. The study focuses on how interaction with English language learners (ELLs) provided preservice teachers with the opportunities to engage in critical reflection, which facilitated construction of their personal second language acquisition research-driven understandings of teaching, learning, and teacher beliefs. This study recommends the use of action research as a tool for helping novice teachers bridge theory and practice and raising awareness of how teacher beliefs and practices impact the teaching of second language learners.