Properties of dual language input that shape bilingual development and properties of environments that shape dual language input
This chapter summarizes several studies of the relation of language input to language development in Spanish-English bilingual children in the U.S., studied from the age of 22 to 30 months. Analyses compare these children to monolingual children from SES-equivalent homes and also examine sources of variability between different groups of bilingual children. The findings suggest that differences in the quantity of input explain differences between bilinguals and monolinguals in the rate of English growth and that differences in the relative quantity and quality of input explain individual differences among bilingual children in their rates of English and Spanish growth. Some of the differences in bilingual children’s language environments can be traced to effects of family composition variables, specifically the presence of school-aged older siblings in the home and whether one or both parents are native Spanish speakers.