This article discusses the current knowledge on the developmental characteristics and contexts of care for infants and toddlers who are growing up in bilingual environments at home and in their early care settings in the united States. The authors highlight relevant findings from the work of the Center of Early Care and Education Research-Dual Language Learners (CECER-DLL), a national research center funded to advance the research field to improve assessment, child care, and education for dual language learners (DLLs) from birth through 5 years old.