Purpose: For many school-age children, teachers are the first professionals to refer for speech/language services. However, many speech-language pathologists note that students without language disorders who speak non-mainstream American English (NMAE) dialects are referred to speech/language evaluation. This research note presents results of a preliminary study exploring teachers' ability to report student dialect use and how teacher reports of language ability depend on their perception of the student's dialect use. Method: Teachers completed a brief two-question survey about students' dialect use and a standardized questionnaire about students' language and literacy skills for 254 students (K-second grades). A subset of 30 students completed a standardized screener of dialect use and language ability. Results: Teachers reported that 12.2% of students spoke an NMAE dialect, whereas 77.2% did not. In sharp contrast, the Diagnostic Evaluation of Language Variation-Screening Test indicated that 63% of students spoke an NMAE dialect, and 37% spoke MAE, suggesting a discrepancy between teachers' perceptions of dialect use and children's dialect use. Written responses suggested teachers may confuse NMAE dialect use and bilingualism or speech/language difficulties. Interestingly, teachers reported lower language skills among students they believe speak an NMAE dialect (p = 0.021). Conclusions: These results provide preliminary evidence that teachers may have difficulty determining student dialect use and may report lower language skills for students they believe speak an NMAE dialect. Interprofessional collaborations between teachers and speech-language pathologists may be able to reduce the likelihood of misdiagnosis of language disorders among students who speak NMAE dialects.