Purpose: This study compared English grammatical performance of bilingual school-age children who spoke either Spanish or Vietnamese at home, focusing on their first-language influence on the acquisition of 13 English grammatical forms. Method: Scores from 30 children on a cloze task were analyzed for accuracy, developmental patterns, and error types. Pairwise matching was used to match individual Vietnamese and Spanish bilinguals on age and English experience. Caregivers rated language ability and daily use of the home language and English. Results: Higher grammatical accuracy across groups was associated with older age and higher caregiver ratings of children's language ability. Groups showed similar patterns on some grammatical forms (e.g., higher accuracy on plurals than irregular past), consistent with previously reported developmental patterns of monolingual English-speaking children. Differences in other patterns were related to first-language influence. For example, phonological constraints of Vietnamese (e.g., no word-final /s/), led to lower accuracy in English forms requiring such sounds. Conclusions: English grammatical performance in bilinguals can reflect both general developmental patterns and first-language influence. As bilingual children may rely on linguistic cues specific to their first language, classroom instruction can be adjusted to be more culturally and linguistically responsive.