Relations between oral language skills and English reading achievement among Spanish-English bilingual children: a quantile regression analysis.

Understanding factors that influence reading achievement among bilingual children is considerably more complex than it is for monolingual children. Research on dual language development indicates that bilingual children's oral language abilities are often distributed across languages in varied ways, due to heterogeneity of dual language exposure and input. Consequently, there may be greater variability in the associations between oral language proficiency and reading achievement among bilingual children than there is for monolingual children. This study evaluated how vocabulary knowledge and morphosyntactic ability in Spanish and English were associated with English reading achievement among 117 bilingual kindergarten and first grade children in the USA using both OLS and quantile regression. Results indicated that although English vocabulary and morphosyntax were both significantly associated with reading achievement, English vocabulary knowledge was most strongly associated with reading at higher quantiles of reading achievement. Cross-language analyses indicated that both Spanish vocabulary and morphosyntax made significant contributions to predicting English reading achievement beyond the effects of English oral language. Spanish vocabulary was uniquely predictive of reading at high and low quantiles of English reading, whereas relations between Spanish morphosyntax and English reading did not differ across quantiles. These results were consistent with predictions derived from theoretical models such as the simple view of reading and suggest that Spanish vocabulary knowledge may provide more unique information about children's underlying capacity for acquiring language and literacy skill than does morphosyntax.