Previous studies show that even though monolingual children find subject relatives easier than object relatives, their comprehension of object relatives can be facilitated by morphological cues. Given that in heritage contexts functional morphology is a vulnerable domain, a question that needs to be addressed is whether bilingual children, who are heritage speakers of their L1, will also be able to use morphological cues to comprehend complex syntax. To contribute to this line of research, we focused on monolingual (N = 18; Mean Age: 11.43) and bilingual/first generation (N = 108; Mean Age: 11.98), Syrian Arabic-speaking children in Canada, and examined their ability to use gender morphology in their comprehension of relative clauses, while taking into consideration cognitive, environmental, and age-related variables. To this end, we used two offline sentence-picture matching tasks targeting relative clauses and gender (as encoded in SV agreement and object clitics). Results showed that, like monolingual children, first-generation, Arabic-speaking children living in Canada used morphological cues to comprehend complex syntax in their L1. Furthermore, even though there was an association between comprehension of gender agreement and comprehension of relative clauses, performance in gender agreement was higher than performance in relative clauses, suggesting that challenges with complex syntactic structures are not necessarily an epiphenomenon of a morphological deficit.

Bilingual children are a more heterogenous group than their monolingual counterparts with respect to the sources of variation in their language learning environments, as well as the wide individual variation in their language abilities. Such heterogeneity in both individual difference factors and language abilities argues for the importance of an individual differences approach in research on bilingual development. The main objective of this article is to provide a review and synthesis of research on the sources of individual differences in the second language (L2) and heritage language (HL) development of child bilinguals. Several child-internal and child-external individual difference factors are discussed with respect to their influence on children’s dual language abilities. In addition, the emergent research on individual differences in bilingual children with developmental language disorder is reviewed. Both the theoretical and applied relevance of individual difference approaches to bilingual development are discussed.

Children with autism spectrum disorder (ASD) show heterogeneous language profiles beyond early language delays. Understanding the second language profiles of bilingual children with ASD is important for clinical practice in diverse societies. Accordingly, we examined the narrative abilities of bilinguals with ASD, with developmental language disorder (DLD), and with typical development (TD) to determine which narrative components best differentiate bilinguals with ASD from the other groups. Participants were 29 bilingual children with ASD, DLD, and TD who were matched for age (mean = 6;8), nonverbal intelligence, and receptive vocabulary. Narratives were coded for macrostructure (story grammar (SG) scores, number of individual SG components) and microstructure (syntactic complexity, mean length of utterance, lexical diversity, and story length). The TD group had superior SG scores, included more SG components, and used longer utterances and more complex syntax than the ASD group, whereas no differences were found between the clinical groups. For SG components requiring perspective-taking abilities, the ASD group had worse performance than the TD and DLD groups. Our results suggest that bilingual children with ASD show weaknesses in both macrostructure and microstructure, which can overlap with children with DLD. The linguistic profiles of bilingual children with ASD and DLD are thus both overlapping and distinct.

First-generation refugee children often experience pre- and post-migration adversity and display high levels of mental health/wellbeing difficulties, but to date, research has not examined the impact of such factors on refugee children's L2 acquisition. Accordingly, this study examined the influence of externalizing and internalizing problem behaviours (wellbeing), time in refugee camps and low socioeconomic status (SES) (adversity) on the English-L2 abilities of 117 Syrian refugee children (7–14 years) in their third year of residency in Canada. Wellbeing difficulties and adversity factors accounted for variance on L2 vocabulary, morphosyntax, listening comprehension and narrative production tasks, beyond the variance accounted for by age of L2 acquisition and length of L2 exposure. Specifically, externalizing problem behaviours, time in refugee camp, maternal education and maternal employment predicted variance in L2 abilities. It is concluded that refugee children could have influences on their L2 acquisition that are different from those of bilinguals with other backgrounds.

The current study sought to investigate whether word properties can facilitate the identification of developmental language disorder (DLD) in sequential bilinguals by analyzing properties in nouns and verbs in L2 spontaneous speech as potential DLD markers. Measures of semantic (imageability, concreteness), lexical (frequency, age of acquisition) and phonological (phonological neighbourhood, word length) properties were computed for nouns and verbs produced by 15 sequential bilinguals (5;7) with DLD and 15 age-matched controls with diverse L1 backgrounds. Linear mixed modelling revealed a significant interaction of group and word category on phonological neighbourhood values but no differences across imageability, concreteness, frequency, age of acquisition, and word length measures in spontaneous speech. Outcomes suggest that group-level differences may not be apparent at the word-level, due to the heterogeneous nature of DLD and potential similarities in production during early L2 acquisition.

Children who are refugees become bilingual in circumstances that are often challenging and that can vary across national contexts. We investigated the second language (L2) syntactic skills of Syrian children aged 6-12 living in Canada (n = 56) and the Netherlands (n = 47). Our goal was to establish the impact of the first language (L1 = Syrian Arabic) skills on L2 (English, Dutch) outcomes and whether L1–L2 interdependence is influenced by the length of L2 exposure. To measure L1 and L2 syntactic skills, cross-linguistic Litmus Sentence Repetition Tasks (Litmus-SRTs) were used. Results showed evidence of L1–L2 interdependence, but interdependence may only surface after sufficient L2 exposure. Maternal education level and refugee camp experiences differed between the two samples. Both variables impacted L2 outcomes in the Canadian but not in the Dutch sample, demonstrating the importance to examine refugee children’s bilingual language development in different national contexts.

Despite growing research on individual differences in child bilinguals, few studies have focused on the development of syntax, included both languages, and studied newly arrived school-age migrant children. Accordingly, this study investigated the syntactic development of heritage language (HL) Syrian Arabic and L2 English by Syrian refugee children (N = 119) recently arrived in Canada using a sentence repetition task. Regression analyses showed that a partially overlapping set of child-level (input and cognitive skills) and language-level (syntactic structure) factors accounted for performance in each language. HL performance was particularly sensitive to language, cognitive, and input variables indexing cumulative HL exposure. L2 performance, however, was sensitive to cognitive and environmental variables indexing current and cumulative L2 use. Finally, despite stronger performance in Arabic than in English, results revealed interdependence between the two languages, indicating that participants with stronger syntactic abilities in their HL tended to have stronger syntactic abilities in their emerging L2.

Word reading is a fundamental skill in reading and one of the building blocks of reading comprehension. Theories have posited that for second language (L2) learners, word reading skills are related if the children have sufficient experience in the L2 and are literate in the first language (L1). The L1 and L2 reading, phonological awareness skills, and morphological awareness skills of Syrian refugee children who speak Arabic and English were measured. These children were recent immigrants with limited L2 skills and varying levels of L1 education that was often not commensurate with their ages. Within- and across-language skills were examined in 96 children, ages 6 to 13 years. Results showed that phonological awareness and morphological awareness were strong within-language variables related to reading. Additionally, Arabic phonological awareness and morphological processing were strongly related to English word reading. Commonality analyses for variables within constructs (e.g., phonological awareness, morphological awareness) but across languages (Arabic and English) in relation to English word reading showed that in addition to unique variance contributed by the variables, there was a high degree of overlapping variance.

Canada has resettled more than 57,000 Syrian refugees since 2015 (Government of Canada, 2017). However, little is known about refugee children’s language and literacy development. The present study evaluated Syrian refugee children’s performance on language and literacy measures in English and Arabic, and examined whether the simple view of reading model is applicable in both of their languages. Participants consisted of 115 Syrian refugee children 6–13 years of age. They received a battery of language and literacy measures including word reading, vocabulary, oral narratives, and reading comprehension in both English and Arabic. Compared to the normative samples, refugee children performed poorly on English standardized measures. They also demonstrated difficulties in Arabic, as more than half of the children were not able to read in the language. Despite the relatively low performance, there was evidence to support the simple view of reading model in both languages. In addition, oral language skills played a larger role in English reading comprehension in the older group than the younger group. This age-group comparison was not carried out in Arabic due to reduced sample size. Theoretical and practical implications of the findings are discussed.

Research on the bilingual development of refugee children is limited, despite this group having distinct characteristics and migration experiences that could impact language development. This study examined the role of language environment factors, alongside age and cognitive factors, in shaping the Arabic as a first/heritage language and English as a second language of recently arrived Syrian refugee children in Canada (N = 133; mean age = 9 years old; mean family residency = 23 months). We found that Arabic was the primary home language with some English use among siblings. Children did not engage frequently in language-rich activities in either language, especially not literacy activities in Arabic. Parent education levels were low: most had primary school only. Hierarchical regression models revealed that stronger nonverbal reasoning skills, more exposure to English at school, more sibling interaction in English, more frequent engagement in language-rich activities in English, and higher maternal and paternal education were associated with larger English vocabularies and greater accuracy with verb morphology. Arabic vocabulary and morphological abilities were predicted by older age (i.e., more first/heritage language exposure), stronger nonverbal reasoning skills and maternal education. We conclude that proximal environment factors, like language use at home and richness, accounted for more variance in the second language than the first/heritage language, but parent factors accounted for variance in both languages.

Previous research has established that early second language (L2) learners in classroom immersion may not ultimately produce all L2 morphosyntactic features as first language (L1) speakers of the language do, whereas L2 comprehension outcomes are reported to be less divergent from those of L1 speakers. However, immersion learners’ L2 comprehension is typically assessed using tasks of holistic understanding, and therefore, little is known about fine-grained comprehension of specific morphosyntactic constructions. To address this, the present study examined online comprehension of English plural–singular marking by Mandarin-speaking, English-immersion learners in Taiwan. This semantically transparent feature differs from the L1 grammar and is a notable area of difficulty for Mandarin-speaking L2-English learners. The present study assesses middle school-aged immersion learners’ comprehension using a visual-world eye-tracking task combined with a picture decision task, comparing results to age-matched English-monolingual controls. After more than 8 years of L2 exposure, the immersion participants showed similarities and differences to monolinguals in plural–singular marking comprehension as measured by eye-tracking, and were less accurate in their interpretations on the picture decision task. This study shows that comprehension differences for a semantically transparent morphosyntactic construction can be apparent even after many years for learners who started immersion at an early age.

Previous research suggests that increased second language (L2) input at home may not support L2 acquisition in children from migrant backgrounds. In drawing this conclusion, existing work has largely aggregated across family members. This study contrasts the effect of L2 input from older siblings with that from mothers. Participants were 113 child L2 learners of English (mean age = 5;10 [range 4;10–7;2]; mean exposure to L2 in school = 16.7 months [range 2–48 months]). All children had at least one older sibling. Using hierarchical linear regression modelling with controls for age, non-verbal reasoning and phonological short-term memory, we found that greater L2 input from siblings – but not mothers – was associated with stronger L2 abilities in narrative macrostructure, inflectional morphology, and vocabulary. Increased cumulative exposure to the L2 at school and greater maternal L2 fluency were also positively related to children's L2 inflectional morphology and vocabulary scores.

It is often claimed that child English L2 learners take up to seven years to attain English skills commensurate with those of monolingual peers; however, existing research is insufficient to know if this claim is valid for oral language abilities in particular. This study examined the lexical and morphological abilities of English L2 learners and their monolingual peers (ages 12–15; N = 227) in Canadian middle schools to determine the timeline for convergence with monolinguals, and what factors predict individual differences among L2 learners. Having seven or more years of schooling was insufficient for all L2 learners to converge with monolinguals on all measures; moreover, growth in English abilities slowed after seven years. Regression analyses revealed that use of English with friends, parental education, and cognitive skills predicted individual variation in the L2 learners’ English abilities and, thus, contributed to their potential for convergence with monolinguals.

This study investigates the role of parental input quality on the acquisition of Greek as a heritage language in Western Canada. Focusing on subject use, we tested four groups of Greek speakers: monolingual children, heritage children, and the parents of each one of those groups. Participants completed an elicited production task designed to elicit subject placement in wide focus and embedded interrogative contexts, where postverbal subjects are preferred/required in the monolingual variety. Results gave rise to two main conclusions: first, the parental input received by heritage children may be qualitatively different from the parental input received by monolingual children, in that it contains a higher rate of deviant preverbal subjects. Second, parental input quality in addition to quantity may affect the outcome of heritage language acquisition, in that children producing a higher rate of preverbal subjects had parents whose Greek input was not only quantitatively reduced, but also richer in preverbal subjects.

The goal of this study was to determine (a) the similarities and dissimilarities between child L2 and L1 acquisition of complex sentences and (b) the individual difference factors predicting L2 children's acquisition of complex sentences. We analyzed language samples from 187 English L2 children with diverse L1s (Agemean = 5;10 [years;months]; English exposuremean = 17 months). Children used various types of complex sentences at all levels of L2 exposure, including sentences with relative clauses, which are late-acquired by L1 learners. Mixed logistic regression modeling revealed that longer exposure to English in school, richer English environments outside school, larger L2 vocabulary, superior verbal memory and visual analytic reasoning contributed to greater use of complex sentences. L1 typology did not impact complex sentence use in the L2. Overall, L2 children used more complex sentences within a few months of English L2 exposure than what is reported for L1 children aged 2;0–4;0, revealing an advantage for an older age of acquisition. The predictive role of input and cognitive factors, as well as vocabulary, in children's use of complex sentences is more consistent with constructivist than generativist accounts of L2 syntactic acquisition.

The cumulative effects hypothesis (CEH) claims that bilingual development would be a challenge for children with specific language impairment (SLI). To date, research on second language (L2) children with SLI has been limited mainly to their early years of L2 exposure; however, examining the long-term outcomes of L2 children with SLI is essential for testing the CEH. Accordingly, the present study examined production and grammaticality judgments of English tense morphology from matched groups of L2 children with SLI and L2 children with typical development (TD) for 3 years, from ages 8 to 10 with 4–6 years of exposure to English. This study found that the longitudinal acquisition profile of the L2 children with SLI and TD was similar to the acquisition profile reported for monolinguals with SLI and TD. Furthermore, L2-SLI children's accuracy with tense morphology was similar to that of their monolingual age peers with SLI at the end of the study, and exceeded that of younger monolingual peers with SLI whose age matched the L2 children's length of exposure to English. These findings are not consistent with the CEH, but instead show that morphological acquisition parallel to monolinguals with SLI is possible for L2 children with SLI.

While age of acquisition effects have been researched extensively in adult second language (L2) acquisition, there is less research focused on examining age of acquisition effects in child language learners. Importantly, for child learners, delays in exposure to language can occur not only for a second but also for a first language (L1). In regard to delays in exposure, it is a widespread assumption that these are detrimental to language outcomes, and that younger is always better for successful language learning. One of the aims of this special issue was to take a closer look at the evidence for this assumption with respect to language learning within the childhood years, both for delayed L1 and L2 exposure.

Carroll (Carroll) takes issue with the use of parent report to obtain quantity of language exposure measures in research on bilingual development. When discussing parent questionnaires, Carroll writes “Temporal units are crude measures of exposure and they tell us nothing about input”. While I agree that temporal units do not tell us much about the fine-grained details of the input within the temporal units, importantly, parent-report-based measures of input quantity have predicted variation in bilingual development of phonology, vocabulary and morphosyntax. These are robust and reliable findings across numerous studies, and yet, Carroll skates over them as if they did not matter, or dismisses them as trivial. Furthermore, Carroll seems to lead readers to believe that only coarse-grained, language-use temporal units have been obtained through this method; on the contrary, researchers have obtained fine-grained input quality details via parent report that also predict bilingual children's development. Finally, in some circumstances, parent report data is the only feasible method for obtaining language exposure information.