Propelled by immigration, language diversity is increasing in the United States, and more young children are exposed to two or more languages at home from birth. Known as dual language learners (DLLs), the benefits of this exposure include multilingual and multiliterate outcomes. However, DLLs introduce complexity for the pediatric provider\'s assessment of language development, identification of potential language delays, and timely referrals. If language delays are not promptly identified and followed with early intervention, they can persist and lead to poor outcomes across multiple domains.

The present study investigated school readiness in Brazilian (Portuguese-Japanese dual language learner or DLL) 5-year-olds in Japan (1) by examining their language skills, executive function (EF), and theory of mind (ToM) in comparison to their monolingual peers and (2) by investigating the developmental relations between these three skills. DLLs scored lower than monolinguals in Japanese language skills, specifically in receptive vocabulary and the understanding of complement clauses in Japanese. DLLs and monolinguals performed similarly in EF, particularly in inhibitory control tasks measuring interference suppression and response inhibition. However, monolinguals outperformed DLLs in ToM tasks assessing false belief understanding. Finally, DLLs\' interference suppression and understanding of complement clauses were both positively related to their false belief understanding. In conclusion, DLLs had school readiness difficulties in Japanese language skills and ToM, but not in EF, compared to their Japanese monolingual peers. Furthermore, the positive relationship of language and EF skills with ToM development, which is commonly reported in monolingual children, extended to an understudied population of DLLs in this study.

This study examines the lexical-grammatical relation within and across in preschool Latino dual language learners (DLLs) with and without specific language impairment (SLI) using language-specific vocabulary and conceptual lexical-semantic skills. The participants were sixty-one typically developing (TD) Spanish-English speaking DLLs and seventy-four DLLs with SLI from low-income households. Standardized and researcher developed assessment tools were used to measure vocabulary, semantics, and grammar in both Spanish and English. Cross-sectional data were analyzed using hierarchical linear regressions to determine the nature of the lexical-grammatical association within and across languages. The study found significant within-language relations between measures of vocabulary and grammar for both groups. Conceptual vocabulary was a significant predictor for English grammar in both groups. For the SLI group only, both English and Spanish vocabulary scores significantly predicted English grammar and bilingual semantics scores predicted Spanish grammar. These findings underscore the role of language-specific vocabulary on grammatical development and suggest the presence of bilingual bootstrapping in DLLs. However, the degree and nature of cross-linguistic associations vary by language ability and language proficiency. The role of age and nonverbal cognition and clinical implications are also discussed.

The present longitudinal study evaluates the effect of effortful control (EC) as a core dimension of temperament on early language competence. We assume that first and second language competence is influenced by EC, and that immigrant children with low EC are thus at risk of an unfavorable language development. The sample consisted of n = 351 dual language learners (DLLs) with an immigrant background and n = 78 monolingual children. Language competence was measured with a standardized language test at age 4.9 years and at age 6.3 years. EC was captured with the Child Behavior Questionnaire, completed by teachers. Results of regression analyses revealed a significant effect of EC on second language development. DLLs with lower EC were found to have not only lower language competence at the beginning and the end of kindergarten but also a less favorable language development. Comparisons between the effect of EC on first and second language provide evidence that EC plays a bigger role in subsequent second language competence compared to first language competence. Overall, the results emphasize the small yet significant role of EC in the second language development of DLLs.

The increasing population of dual language learners (DLLs) entering preschool classrooms highlights a continued need for research on the development of dual language acquisition, and specifically vocabulary skills, in this age group. This study describes young DLL children\'s (N = 177) vocabulary development in both English and Spanish simultaneously, and how vocabulary skills in each language relate to one another, during a contextual shift that places greater emphasis on the acquisition of academic English language skills. Findings demonstrated that DLL preschoolers made gains in vocabulary in both languages with more change evidenced in receptive, in comparison to expressive, vocabulary as well as in English in comparison to Spanish. When examining whether children\'s vocabulary scores in one language at the beginning of preschool interact with their vocabulary scores in the other language to predict vocabulary growth, no significant associations were found for receptive vocabulary. In contrast, the interaction between initial English and Spanish expressive vocabulary scores was negatively related to growth in English expressive vocabulary. This cross-language association suggests that children who have low expressive vocabulary skills in both languages tend to grow faster in their English expressive vocabulary. The study extends previous work on dual language development by examining growth in expressive and receptive vocabulary in both English and Spanish. It also provides suggestions for future work to inform a more comprehensive understanding of DLL children\'s development in both languages.

Dual language exposure and bilingualism are relatively common experiences for children. The present review set out to synthesize the existing research on cognitive development in bilingual children and to identify the gaps and the methodological concerns present in the existing research. A search of major data bases for research conducted with typically-developing, preschool-age dual language learners between 2000-2013 yielded 102 peer-reviewed articles. The existing evidence points to areas of cognitive development in bilingual children where findings are robust or inconclusive, and reveals variables that influence performance. The present review also identifies areas for future research and methodological limitations.