Purpose: This study was designed to assess the utility of a tool for automated analysis of rare vocabulary use in the spoken narratives of a group of school-age children from low-income communities. Method: We evaluated personal and fictional narratives from 76 school-age children from low-income communities (M[subscript age] = 9;3 [years;months]). We analyzed children's use of rare vocabulary in their narratives, with the goal of evaluating relationships among rare vocabulary use, performance on standardized language tests, language sample measures, sex, and use of African American English. Results: Use of rare vocabulary in school-age children is robustly correlated with established language sample measures. Male sex was also significantly associated with more frequent rare vocabulary use. There was no association between rare vocabulary use and use of African American English. Discussion: Evaluation of rare vocabulary use in school-age children may be a culturally fair assessment strategy that aligns well with existing language sample measures.