Multitiered systems of support hold promise for dual language learners when culturally and linguistically responsive practices guide instruction. We modeled growth on Spanish and English early literacy skills and examined the role of language exposure and use at the individual and classroom instruction level in a group of 313 Spanish-English-speaking bilingual preschool-age children from 81 classrooms. Results revealed a significant portion of variance in children's performance was between classrooms. Children demonstrated meaningful growth on all measures except English rhyming. Predominantly Spanish and bilingual instruction produced growth as strong as English instruction on all measures except for first sounds and sound identification where bilingual instruction had a negative impact on growth. Children's language profiles did not interact with their classroom language of instruction. Implications for understanding the role language of instruction and home language exposure in multitiered systems of support with Spanish-speaking preschoolers are discussed. [For the corresponding grantee submission, see ED619379.]