Purpose The purpose of the current study was to evaluate the effect of bilingual narrative intervention on vocabulary gains in Hebrew (school language) and English (home language) among English–Hebrew bilinguals, using a block design (one language at a time), and to determine whether there was cross-linguistic transfer to the language that was not receiving intervention. Method Sixteen English–Hebrew bilingual children participated in the study using an adaptation of the Puente de Cuentos intervention. Vocabulary was examined using a word definition task before the intervention, post English intervention, post Hebrew intervention, and 4 weeks after the interventions ended to examine maintenance of skills. Results Repeated-measures analyses of variance revealed that children made significant gains in vocabulary in the language of intervention as expected. In addition, children made cross-linguistic gains in Hebrew during the English intervention, but made no gains in English following Hebrew intervention. Conclusion These results underscore the need to provide language support in the home language to ensure growth and that intervention in the home language does not hinder growth in the school language.

Introduction: Research in recent years has explored the vocabulary size (lexical breadth) of bilingual children, but less is known about the richness of bilingual word knowledge (lexical depth), and about how knowledge of words in the two languages interact. This study explores how bilingual narrative intervention with vocabulary instruction in each language may modulate crosslinguistic influence (CLI) between the languages of bilingual kindergarten children, focusing on CLI of lexical knowledge, and which factors modulate performance.Methods: Forty-one typically developing English-Hebrew bilingual children (M = 64.63 months) participated. A bilingual adaptation of Story Champs narrative intervention program (Spencer and Petersen, 2012) was used to deliver vocabulary instruction in separate blocks of home language (HL) and school language (SL) sessions. Different intervention words were targeted in each language, but the children were tested on all target words in both languages. Lexical knowledge was assessed with a definition task four times throughout the study: prior to intervention, after each intervention block, and 4–6 weeks later. Learner characteristics (chronological age, age of onset of bilingualism and length of exposure) and proficiency in each language (standardized tests, familiarity with the vocabulary introduced in the intervention at baseline) were examined as possible modulators of performance.Results: Children showed growth in lexical breadth and depth in their HL/English after HL intervention and in lexical breadth in the SL/Hebrew following SL intervention, with CLI for semantic depth observed via a qualitative analysis, but not quantitatively. Better HL/English performance was correlated with later AoB (and shorter SL exposure) and higher HL language proficiency scores. Children with higher HL/English proficiency responded better to the SL/Hebrew intervention, gaining more than those with lower English proficiency. Children with SL/Hebrew vocabulary dominance at the outset of the study also gained more from the HL/English intervention. No correlations were found between learner characteristics and SL performance.Discussion: The current study indicates that bilingual narrative intervention with vocabulary instruction may be efficacious for improving the lexical breadth and depth of bilingual kindergarten children. It suggests that CLI may enhance bilingual children’s language learning success, and points to the importance of strengthening both languages of bilingual children.