Family constellation and language experience as influences on bilingual first language acquisition

This study investigated the effects of family composition and properties of children's dual language exposure on bilingual first language acquisition. Mothers of 29 toddlers (13 boys and 16 girls, M age = 25.66 months, SD = .44) kept a language diary, providing measures of the amount, the contexts, and the persons with whom the children experienced English and Spanish. Measures of the children's vocabulary balance were obtained from English and Spanish language inventories. Results showed that only children with two native Spanish-speaking parents had larger Spanish than English vocabularies and experienced more hours of Spanish-only exposure and Spanish-only conversational contexts. Analysis of covariance demonstrated that the effect of family composition on vocabulary balance was completely mediated by the balance of English and Spanish in the children's language exposure. There was no evidence of a unique effect of experiencing Spanish-only conversational contexts or partners on children's acquisition of Spanish.