Purpose: This study investigated the dimensionality of language in bilingual children using measures of semantics and morphosyntax in English and Spanish. Method: Participants included 112 Spanish-English bilingual children ages 4-8 years from a wide range of language abilities and dominance profiles. Using measures of semantics and morphosyntax from both norm-referenced assessments and language samples, we evaluated the structure of language in bilingual children. We used confirmatory factor analysis (CFA) to estimate dimensionality, comparing seven primary models that represented different theoretical structures of language in bilinguals. Results: Although none of the models analyzed yielded good fit across all indices evaluated, the best-fitting CFA model was a two-correlated factor model with separate factors for Spanish and English, which included measures from only norm-referenced assessments. Conclusions: Language in Spanish-English children seems to represent two related but distinct constructs, even in bilinguals from a wide range of language abilities and dominance profiles. Clarifying how language in bilinguals is conceptualized and impacted by the concurrent development of two languages is an area that requires further research. Understanding the dimensionality of language in bilinguals can further assist our knowledge of how language develops in bilingual children.