Purpose The purpose of this study was to determine if a standardized assessment developed for Spanish–English dual language learners (SEDLLs) differentiates SEDLLs with language impairment (LI) from children with typical language better than the translated/adapted Spanish and/or English version of a standardized assessment and to determine if adding informal measure/s to the standardized assessment increases the classification accuracy. Method Standardized and informal language assessment measures were administered to 30 Mexican American 4- to 5-year-old SEDLLs to determine the predictive value of each measure and the group of measures that best identified children with LI and typical language. Discriminant analyses were performed on the data set. Results The Morphosyntax and Semantics subtests of the Bilingual English–Spanish Assessment ( Peña, Gutierrez-Clellen, Iglesias, Golstein, & Bedore, 2014 ) resulted in the largest effect size of the individual assessments with a sensitivity of 93.3% and a specificity of 86.7%. Combining these subtests with mean length of utterance in words from the child's better language sample (English or Spanish) was most accurate in identifying LI and can be used with above 90% confidence. Conclusion The Bilingual English–Spanish Assessment Morphosyntax and Semantics subtests were shown to comprise an effective measure for identifying LI; however, including a language sample is suggested to identify LI with greater accuracy.