Disentangling Experience and Disorder: What Bilingualism Reveals About the Structure of Child Language Development

PURPOSE: This study examined the latent structure, or underlying organization, of semantic and morphosyntactic knowledge in school-age Spanish-English bilinguals and evaluated how age, English exposure, and developmental language disorder (DLD) relate to these latent domains. METHOD: A total of 427 bilingual children completed parallel semantic and morphosyntactic tasks in Spanish and English, including a clinical sample of 77 children with DLD. Confirmatory factor analyses compared four structural models: a unidimensional model, two bidimensional models (by domain and by language), and a four-factor correlated model. Age and exposure effects were evaluated using latent regressions, and measurement invariance was tested across children with and without DLD. RESULTS: The four-factor correlated model best represented bilingual language knowledge, with distinct semantic and morphosyntactic domains in each language. Age and English exposure predicted latent means without evidence of differential item functioning. Children with DLD scored significantly lower on all latent domains, and the level of achieved invariance supported valid cross-group comparisons. CONCLUSIONS: Semantic and morphosyntactic abilities in school-age bilinguals are multidimensional and structurally stable across age, exposure, and DLD status. These findings clarify the organization of representational knowledge in bilingual development and support clinical assessment practices that help school-based speech-language pathologists distinguish experiential variation from underlying impairment. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.34747674.