Mountain Park Elementary School, a pseudonym, near New York City saw a significant increase in newcomer English language learners (ELLs). A third of MPES students achieved proficiency on state assessments compared to 5% of ELLs. The theory of action predicted that if teachers were provided with opportunities to acknowledge and challenge their implicit biases, and implemented specific teaching strategies, teachers would create a culturally responsive learning environment that supported a sense of belonging and risk-taking among newcomer ELLs, who would ultimately help ELLs progress in their social and academic skills. Using a mixed methods improvement science approach, we tested two change ideas over five weeks: (a) providing teachers with professional development for culturally responsive teaching via a multisensory intervention and (b) a book study exploring teacher implicit bias. The research utilized two theoretical frameworks: Bronfenbrenner's ecological systems model and Blanco-Vega's sociocultural systems model. Teachers focused on challenging their own personal biases to create classrooms that showcased the diverse students they taught. In addition, teachers implemented culturally responsive academic strategies combined with explicit teaching, promotion of English language learning, phonemic awareness and decoding, vocabulary development, interactive teaching that maximized student engagement, and instruction that produced opportunities for accurate responses with feedback for struggling learners. Teachers recognized their strengths and challenges, showed willingness to learn and use specific new strategies in the classroom, and engaged in courageous conversations about personal bias. Observations, walkthroughs, and surveys highlighted continued implementation of culturally responsive academic approaches while creating welcoming, inclusive classrooms. [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.]