Purpose: The aim of this study was to examine the performance of a group of Spanish-speaking, dual language learners (DLLs) who were attending English-only schools and came from low-income and low-parental education backgrounds on the Clinical Evaluation of Language Fundamentals--Fourth Edition, Spanish (CELF-4S; Semel, Wiig, & Secord, 2006). Method: Spanish-speaking DLLs (N = 656), ages 5;0 (years;months) to 7;11, were tested for language impairment (LI) using the core language score of the CELF-4S and the English Structured Photographic Expressive Language Test (Dawson, Stout, & Eyer, 2003). A subsample (n = 299) was additionally tested using a Spanish language sample analysis and a newly developed Spanish morphosyntactic measure, for identification of children with LI and to conduct a receiver operating characteristics curve analysis. Results: Over 50% of the sample scored more than 1 SD below the mean on the core language score. In our subsample, the sensitivity of the CELF-4S was 94%, and specificity was 65%, using a cutoff score of 85 as suggested in the manual. Using an empirically derived cutoff score of 78, the sensitivity was 86%, and the specificity was 80%. Conclusions: Results suggest that the CELF-4S overidentifies low-income Spanish-English DLLs attending English-only schools as presenting with LI. For this sample, 1 in every 3 Latino children from low socioeconomic status was incorrectly identified with LI. Clinicians should be cautious when using the CELF-4S to evaluate low-income Spanish-English DLLs and ensure that they have converging evidence before making diagnostic decisions.