Expressive Vocabulary Development in Children from Bilingual and Monolingual Homes: A Longitudinal Study from Two to Four Years.

The early course of language development among children from bilingual homes varies in ways that are not well described and as a result of influences that are not well understood. Here, we describe trajectories of relative change in expressive vocabulary from 22 to 48 months and vocabulary achievement at 48 months in two groups of children from bilingual homes (children with one and children with two native Spanish-speaking parents [ns = 15 and 11]) and in an SES-equivalent group of children from monolingual English homes (n = 31). The two groups from bilingual homes differed in their mean levels of English and Spanish skills, in their developmental trajectories during this period, and in the relation between language use at home and their vocabulary development. Children with two native Spanish-speaking parents showed steepest gains in total vocabulary and were more nearly balanced bilinguals at 48 months. Children with one native Spanish- and one native English-speaking parent showed trajectories of relative decline in Spanish vocabulary. At 48 months, mean levels of English skill among the bilingual children were comparable to monolingual norms, but children with two native Spanish-speaking parents had lower English scores than the SES-equivalent monolingual group. Use of English at home was a significant positive predictor of English vocabulary scores only among children with a native English-speaking parent. These findings argue that efforts to optimize school readiness among children from immigrant families should facilitate their access to native speakers of the community language, and efforts to support heritage language maintenance should include encouraging heritage language use by native speakers in the home.

Total and conceptual vocabulary in Spanish-English bilinguals from 22 to 30 months: implications for assessment.

PURPOSE: Vocabulary assessment holds promise as a way to identify young bilingual children at risk for language delay. This study compares 2 measures of vocabulary in a group of young Spanish-English bilingual children to a single-language measure used with monolingual children. METHOD: Total vocabulary and conceptual vocabulary were used to measure mean vocabulary size and growth in 47 Spanish-English bilingually developing children from 22 to 30 months of age based on results from the MacArthur-Bates Communicative Development Inventory (CDI; Fenson et al., 1993) and the Inventario del Desarrollo de Habilidades Comunicativas ( Jackson-Maldonado et al., 2003). Bilingual children's scores of total vocabulary and conceptual vocabulary were compared with CDI scores for a control group of 56 monolingual children. RESULTS: The total vocabulary measure resulted in mean vocabulary scores and average rate of growth similar to monolingual growth, whereas conceptual vocabulary scores were significantly smaller and grew at a slower rate than total vocabulary scores. Total vocabulary identified the same proportion of bilingual children below the 25th percentile on monolingual norms as the CDI did for monolingual children. CONCLUSION: These results support the use of total vocabulary as a means of assessing early language development in young bilingual Spanish-English speaking children.

Dual language exposure and early bilingual development.

The extant literature includes conflicting assertions regarding the influence of bilingualism on the rate of language development. The present study compared the language development of equivalently high-SES samples of bilingually and monolingually developing children from 1 ; 10 to 2 ; 6. The monolingually developing children were significantly more advanced than the bilingually developing children on measures of both vocabulary and grammar in single language comparisons, but they were comparable on a measure of total vocabulary. Within the bilingually developing sample, all measures of vocabulary and grammar were related to the relative amount of input in that language. Implications for theories of language acquisition and for understanding bilingual development are discussed.