Emergent bilinguals account for a quarter of the approximately 70 million children under age 18 in the US (Esterline & Batalova, 2022). The question of how to serve these children best in educational settings has been contested. A substantial body of research has documented effective practices to promote bilingual development in dual language programs. However, dual language instruction is not possible in all contexts due to the diversity of languages represented among emergent bilinguals (Espinosa, 2013), and little work thoroughly examined effective practices in educational settings where a wider range of languages are spoken. This study addresses this gap by investigating ethnographically informed classroom practices of a preschool teacher in a linguistically diverse classroom to promote the bilingual development of emergent bilinguals. This ethnographically informed case study explores the family language policies of five multilingual families in a Midwestern US city and the subsequent development of early childhood classroom practices for emergent bilinguals. Informed by teacher research (Cochran-Smith & Lytle, 2009), this research examines two critical issues. First, what the focal families' language policies are, including: (1) their language ideologies, (2) contexts that shape their language related decisions, (3) language practices, and (4) language management activities. Second, how the preschool teacher used information about the families' language policies to develop classroom practices for emergent bilinguals. The findings indicate that the preschool teacher's positive attitude toward the emergent bilinguals' family and community language practices translated into her classroom practices and that the teacher drew from her personal and professional funds of knowledge in the construction of her classroom practices for emergent bilinguals. The findings highlight implications for early childhood teacher preparation and professional development programs by providing insights into how an early childhood educator might work with the families of emergent bilinguals to elicit information about their children (e.g., learning about the social, linguistic, and cultural backgrounds of the children) and use that information to develop classroom practices for emergent bilinguals. [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.]