This article examines the unique contributions that bilingual and bilingually credentialed teachers make to the instruction of emergent bilinguals in the United States. This mixed methodological study involved 474 teachers in Arizona, California, and Texas, which represent distinct language policy contexts. Results revealed that, irrespective of context, teachers' bilingualism and bilingual certification significantly predicted their reported use of practices that build on students' primary language as well as their prior knowledge and experiences. Given declining numbers of teachers completing bilingual credentials in English-only states, findings suggest that English-only policies are diminishing the supply of teachers with the potential to improve emergent bilinguals' classroom experiences.