Recent research on second language and subject-matter learning calls for moving away from hegemonic monolingual education in U.S. schools and instead making "translanguaging" the norm by supporting bi/multilingual students to use their full linguistic repertoires as they participate in classroom learning (Garcia, Johnson, & Seltzer, 2017; Seltzer & de los Rios, 2021). "Translanguaging" is a pedagogical approach in which teachers and students flexibly draw on their full language resources to think, make meaning, and learn (Garcia & Li Wei, 2014). To respond to that call, this study explores translanguaging through use of English and Arabic in a 6th grade social studies classroom at a public school in a Midwestern city. I explored how the Arabic-speaking teacher made meaning through translanguaging to support her Arabic-speaking emergent bilingual students while reading and analyzing sources and how the students responded. I analyzed teacher and student interviews and students' written work and recorded translanguaging events from forty-five lessons during four investigations over an academic year. The bilingual inquiry curriculum, bilingual teacher, biliterate peers, and newcomer students (recently-arrived in the U.S.) contributed to making the investigations' content available in Arabic. Translanguaging was mostly motivated by the presence of newcomer students, who were supported by dialogue with others willing to use Arabic. In this context translanguaging occurred in its full meaning of drawing on all speakers' resources for meaning-making. All students develop new language as they learn school subjects. A key finding of this study is that over time, the teacher and students developed their Arabic language resources along with English through participation in inquiry. This means that translanguaging supported them in the important goal of developing as bilinguals and that the learning context offered support in learning through both languages. The study extends Garcia et al.'s (2017) "translanguaging pedagogy classroom framework" to recognize students' agentive role in establishing translanguaging "stance" and initiating/enabling translanguaging "shifts" during content learning, as well as recognizing teacher's planned translanguaging shifts that mediate between students' current/familiar bilingual repertoires and disciplinary bilingual repertoires needed to talk about content. The dissertation also presents a case study of one newcomer learner's development of English, Arabic, and understanding of social studies issues and practices through participation across the year, illustrating how learning was supported through translanguaging. Using bilingual texts and interacting through translanguaging provided him with multiple supports for the disciplinary work, and when paired with a bilingual peer who was motivated to use Arabic, he became an active participant in disciplinary thinking and agentive in demonstrating his social studies learning in Arabic. The dissertation draws implications for further research and teacher education programs. Researchers may assume that when teachers and students speak the same home/community language, translanguaging will be easily taken up. This study identifies supports that are needed even in such contexts to implement translanguaging to its full potential. Further research can continue to explore how both teachers and students develop the disciplinary language that supports subject-matter learning through translanguaging, and how teacher preparation programs can recruit more bilingual teachers and support their full bilingual development for subject-matter teaching. As envisioned in the theory, this study ultimately shows how translanguaging can support the development of students' bilingual repertoires to make meaning, and that implementing translanguaging as a norm in disciplinary classrooms is possible even in the context of hegemonic English in U.S. schools. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]