In recent decades, the share of ethnically and linguistically diverse children enrolled in schools in the United States has exponentially increased. Despite the growing representation of ethnic minority and dual language learner (DLL) children, there is persistent evidence of early vocabulary gaps between low-income and DLL children and their higher-income and language majority peers. In addition, teachers hold diminished perceptions of ethnic minority and DLL children's academic skills. In three papers, this dissertation examines aspects of ethnic and linguistic minority children's classroom experiences that hold implications for children's vocabulary development and teachers' perceptions of their executive functions (EFs). Two papers utilize the nationally representative Head Start Family and Child Experiences Survey (FACES) to examine how the languages used by teachers and peers can promote preschoolers' English vocabulary development while supporting their Spanish vocabulary development. In the first paper, I examine whether the languages used for instruction and the proportion of DLLs in the classroom are associated with DLLs' English and Spanish vocabulary development. Findings hold implications for the optimal balance of English and Spanish for instruction, as well as the composition of classrooms for DLLs. In the second paper, I consider the association between peers' vocabulary ability and DLLs' English and Spanish vocabulary development. I also examine whether these associations vary by DLLs' initial vocabulary skills. Findings hold implications for the creation of mixed ability classrooms and the value of peer-to-peer interactions in preschool. Finally, in the third paper, I examine teachers' perceptions of elementary students' EFs. I test whether teachers' ratings of students' EFs vary systematically as a function of students' gender, ethnicity and English Language Learner status, while controlling for a direct assessment of students' EFs. Moreover, I examine whether these associations change between the fall and spring. Teachers' perceptions of students' executive functions could hold ramifications for students' academic trajectories, and may contribute to minority students' overrepresentation in school discipline and special education. Implications for practitioners and policy-makers are discussed in each paper. [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.]