Research on Spanish-speaking preschoolers suggests that early bilingual supports in both English and Spanish, such as bilingual instruction or access to resources in both languages, are promising practices for supporting DLLs. However, few studies have sufficient longitudinal data to explore which of these bilingual supports matter most for DLLs into elementary school. The proposed project extends this emerging evidence base by conducting the first exploration of longitudinal associations between classroom bilingual supports and developmental outcomes for Spanish- speaking DLLs in the formative earliest years of education. The repeated measurements of both supports and outcomes also facilitates the application of more rigorous statistical methods than has been possible in existing studies. With these data, I will address the following research questions: 1. What is the effect of classroom bilingual supports - Spanish bilingual teacher, use of Spanish in the classroom, and provision of classroom materials in Spanish - in early education on DLLs' language, math, self-regulatory, and achievement outcomes? 2. Do the effects of classroom bilingual supports vary by children's linguistic skills and contexts: specifically, baseline English and Spanish skills and the amount of English relative to Spanish spoken at home? 3. Are effects of classroom bilingual supports mediated by individual children's classroom experiences, including their classroom language context (speaking or listening in English and/or Spanish) and their relationships with their teachers? (author abstract)