Purpose: The aim of this study was to investigate the appropriateness of standardized assessments of expressive grammar and vocabulary in a sample of preschool-age dual language learners (DLLs) who use Jamaican Creole (JC) and English. Adult models from the same linguistic community as these children were used to inform culturally and linguistically appropriate interpretation of children's responses to a standardized assessment. Method: JC-English-speaking preschoolers (n = 176) and adults (n = 33) completed the Word Structure and Expressive Vocabulary subtests of the Clinical Evaluation of Language Fundamentals Preschool--Second Edition. Adults' responses were used to develop an adapted scoring procedure that considered the influence of JC linguistic features on responses. DLLs' responses scored using the standard English and adapted JC procedures were compared. Results: JC-English DLLs and adults used similar linguistic structures in response to subtest questions. DLLs' scores differed significantly from the standardized sample on both subtests. Preschoolers received higher raw and corresponding standard scores with adapted scoring compared to standard scoring. Adapted scoring that made use of adult models yielded high classification accuracy at a rate of 93.8% for Word Structure and 92.1% for Expressive Vocabulary. Conclusions: Adapting standardized assessment scoring procedures using adult models may offer an ecologically valid approach to working with DLL preschoolers that can support a more accurate assessment of language functioning. These findings suggest that the use of standardized assessments for bilingual JC-English speakers requires a culturally responsive approach.