This study compares lexical development in a sample of 25 simultaneous bilingual and 35 monolingual children for whom semilongitudinal data were collected between the ages of 8 and 30 months. A standardized parent report form, the MacArthur Communicative Development Inventory (1989), was used to assess the children's receptive and productive vocabulary in English and/or Spanish. A methodology was devised to assess the degree of overlap between the bilingual children's lexical knowledge in one language and their knowledge in the other. Using the measures presented here, there was no statistical basis for concluding that the bilingual children were slower to develop early vocabulary than was the monolingual comparison group. The wide range of vocabulary sizes observed at these ages in normally developing children (Fenson et al., 1991) was observed in these bilingual children as well. The close correspondence of the pattern of the bilinguals' growth in two languages at once to monolinguals' growth in one suggests that norms for lexical development in bilinguals should be made with reference to the children's performance in two languages together.

The bilingual child is seen as a unique source of information about the relation between input and intake. The strength of the association between language exposure estimates and vocabulary learning was examined for 25 simultaneous bilingual infants (ages 8 to 30 months) with differing patterns of exposure to the languages being learned. Using the MacArthur Communicative Development Inventories, standardized parent report forms in English and Spanish, the percentage of all words that were known in each language was calculated and then plotted against the estimates of language input (also in percentages). A significant correlation was found, r(25)= .82, p < .001. The correlation was also strong when examined point-by-point, even for children whose language environments changed by more than 20%; between observations, although it was not reliable at lower levels of exposure to Spanish. Especially for children with less input in the minority language, the factors which appeared to affect the strength of the association between input and amount learned in a language are discussed.

Bilingual children's language and literacy is stronger in some domains than others. Reanalysis of data from a broad-scale study of monolingual English and bilingual Spanish-English learners in Miami provided a clear demonstration of "profile effects," where bilingual children perform at varying levels compared to monolinguals across different test types. The profile effects were strong and consistent across conditions of socioeconomic status, language in the home, and school setting (two way or English immersion). The profile effects indicated comparable performance of bilingual and monolingual children in basic reading tasks, but lower vocabulary scores for the bilinguals in both languages. Other test types showed intermediate scores in bilinguals, again with substantial consistency across groups. These profiles are interpreted as primarily due to the "distributed characteristic" of bilingual lexical knowledge, the tendency for bilingual individuals to know some words in one language but not the other and vice versa.Childhood bilingualism has been reported to show academic advantages over monolingualism. In optimal circumstances of learning, these advantages have been reported to include, in comparison with monolinguals, at least as good and often better performance by bilinguals in language, literacy, and various realms of cognition (Ben

A number of studies have shown that approximately one-quarter of children in potentially bilingual environments do not become bilingual. This article explores several key factors that influence the likelihood that a child who has access to interactions in two languages will learn them both. The five factors discussed are input, language status, access to literacy, family language use, and community support, including schooling. It is argued that the quantity of input has the greatest effect on whether a minority language will be learned, but language status and attitudes about language also play a role. When families are proactive and provide daily activities for children in the minority language, the children respond by learning it. In addition, dual-immersion, “two-way” schooling is shown to benefit children's level of language proficiency in the minority language without diminishing their progress in the community language.