Bilingualism has been systematically associated with better self-regulatory skills (), however, this advantage does not seem to automatically transfer for most dual language learners. This suggests that there are other contextual factors that are necessary to trigger this advantage. This study examines the role of teacher-child interactions in the development of Spanish-speaking bilingual preschoolers' self-regulation in an English-speaking context, and how this relation differs between bilingual and English-speaking monolingual children. Our study analyzed a sample of 1656 preschoolers in the U. S. and yielded two salient results (1) Bilingual children demonstrated greater gains in self-regulatory skills than their monolingual peers when in classrooms with high-quality teacher-child interactions. (2) Vocabulary in bilingual children moderated the relation between teacher-child interactions and teacher-reported self-regulation for bilingual children, with bilinguals who had greater vocabulary knowledge benefiting more from classroom interactions. These outcomes hold significant implications for policy makers, given the evolving sociodemographic profile of classrooms globally.