Grammatical measures that distinguish language differences from language disorders in bilingual children are scarce. This study examined English past tense morphology in sequential bilingual Spanish/English-speaking children, age 7;0-9;0 (years;months). Twelve bilingual children with language impairment (LI) or history of LI and 15 typically developing (TD) bilingual children participated. Thirty-six instances of the past tense including regular, irregular, and novel verbs were examined using an elicited production task. By examining English past tense morphology in sequential bilinguals, we uncovered similarities and differences in the error patterns of TD children and children with LI. The groups differed in the overall accuracy of past tense use according to verb type, as well as the characteristic error patterns. Children with LI performed lower than their TD peers on all verb categories, with an interaction between verb type and group. TD children were better at producing regular verbs and exhibited more productive errors (e.g., overregularization). Conversely, children with LI performed relatively better on irregular verbs and poorest on novel verbs, and they exhibited more nonproductive errors (e.g., bare stem verbs). The results have important clinical implications for the assessment of morphological productivity in Spanish-speaking children who are learning English sequentially.