This study investigates the role of motivation and learner variables in bilingual vocabulary development among first language (L1) Japanese students attending hoshuukoo (i.e., supplementary academic schools for Japanese‐speaking children) in the United States. One hundred sixteen high school students ages 15–18 from eight hoshuukoo completed Japanese and English vocabulary tests and a student characteristics questionnaire. A principal component analysis identified six motivational factors: preference for Japan, Japanese heritage, no choice, career orientation, American identity, and positive perceptions. The students highly rated career orientation, positive perceptions, and Japanese heritage as reasons to learn both languages. Regression analysis revealed negative effects of American identity and career orientation on L1 Japanese vocabulary knowledge and a positive impact of positive perceptions on second language (L2) English proficiency. The students' college plans were highly related to the motivational factor of preference for Japan. In sum, bilingual competence can be related to motivational factors, and individual differences in bilingual proficiency among young learners of Japanese as a heritage language can be, at least partially, accounted for by socio‐psychological factors.

This study examines bilingual vocabulary knowledge in relation to arrival age among first language (L1) Japanese students attending hoshuukoo (i.e., supplementary academic schools for Japanese-speaking children) in the United States. It also examines the relationship between L1 Japanese and English as a second language (L2), as motivated by Cummins's (1979Cummins's ( , 1991 notion of linguistic interdependence. One hundred and twenty-two high school students ages 15-18 from eight hoshuukoo took Japanese and English vocabulary tests designed by Ono (1989). Students who came to the United States by age 9 or younger were three grades behind in L1 Japanese and were either ahead of or at their U.S. grade level in English. In contrast, those who arrived at age 10 or older were just one grade behind in Japanese and were two to five years behind in English. High vocabulary knowledge in one language was associated with low knowledge in the other, and the negative correlation between L1 and L2 became statistically nonsignificant when arrival age was controlled. Consequently, arrival age remains an important factor in accounting for hoshuukoo students' bilingual vocabulary learning, and the notion of linguistic interdependence must be reexamined in factors in addition to vocabulary knowledge.Technology (MEXT), the number of elementary and middle school children living abroad for over three months was only 6,662 in 1971, but it has been steadily increasing since then and reached 64,950 in 2012. Roughly speaking, one third of those children reside in North America (21,280), another one third live in Asia (26,498), one sixth stay in Europe (12,069), and the remaining children reside in other parts of the world (MEXT, 2012, n.p.).The statistics also show substantial differences between regions in the types of educational institutions that children of Japanese as a first language (L1) attend. In North America, it is reported that 45.0% of L1 Japanese children attend both local schools and hoshuukoo 1 -extracurricular supplemental schools that provide academic instruction in Japanese, 53.2% attend local school only, and 1.8% attend full-day Japanese school where students receive academic instruction exclusively in Japanese throughout the week. In Asian countries, in contrast, it is reported that 55.5% attend full-day Japanese school, 41.1% attend local school only, and 3.4% attend hoshuukoo. As most hoshuukoo provide only limited hours of instruction during weekends, students who report that they attend hoshuukoo are most likely to attend local school on weekdays. In other words, more than 98% of L1 Japanese children residing in North America receive school instruction mainly in English, their second language (L2), 2 and limited academic instruction in their L1 if they attend hoshuukoo, whereas a majority of L1 Japanese children residing in Asian countries receive school education in Japanese.What does growing up in an L2-dominant environment mean to L1 Japanese children in terms of their language development? What impact does sc...

This study investigated the role of parental support and selected family variables in the first (L1) and second language (L2) vocabulary development of Japanese heritage language (JHL) high school students in the United States. Eighty‐two JHL students ages 15–18 from eight hoshuukoo (i.e., supplementary academic schools for Japanese‐speaking children) were assessed for their L1 Japanese and L2 English vocabulary knowledge. Simultaneously, the students’ parents, at least one of whom was a Japanese native, completed a family background questionnaire. An exploratory factor analysis identified five components that the parents considered effective for supporting their children's language development: Japanese pop culture, reading for pleasure in Japanese, use of Japanese at home, reading to the child, and family conversation. Regression analyses revealed that reading for pleasure in Japanese positively predicted the students’ L1 Japanese vocabulary and that Japanese pop culture negatively predicted their L2 English vocabulary. L1 Japanese vocabulary was also predicted by students’ dominant language and parents’ goals for their children's achievement, whereas L2 English vocabulary was predicted by future residency plan, mother's self‐rated English proficiency, and home language use. In short, JHL students’ L1 Japanese and L2 English vocabulary development involves different family factors. Consequently, different approaches should be recommended to support HL students’ L1 and L2 development.