This study analyzed the grammatical control of verbs exercised by 145 monolingual English and Generation 1.5 bilingual developmental writers in narrative essays using quantitative and qualitative methods. Generation 1.5 students made more errors than their monolingual peers in each category investigated, albeit in only 2 categories was the difference statistically significant. Yet the overall effect was cumulative: The total number of verb errors in the essays of bilinguals was statistically larger than that in the essays of monolinguals. Both monolingual and bilingual writers inappropriately transferred the features of spoken English into the written medium, and both displayed difficulties in the appropriate use of the perfect aspect. However, Generation 1.5 learners also exhibited ESL-like traits in their writing, demonstrating a weak control of verbal inflection. The findings suggest that explicit grammar instruction may be warranted in all Developmental Writing classes, especially those with large proportions of Generation 1.5 learners.