Abstract Objective The D-KEFS Verbal Fluency Test (VF) is a commonly used measure of a variety of executive functions with three separate components: Letter Fluency (FAS), Category Fluency and Category Switching. This study will solely explore the FAS, a measure of phonemic fluency and lexical access. Prior research in cognitively impaired adults suggested a potential for a short-form version of the test. This project seeks to validate these findings across different age groups. The hypothesis predicts a positive correlation between words produced in the 1–15 second interval for the letter F and the total FAS score, which includes three 60-second intervals for each letter. Method The study involved 99 patients aged 10 to 88 (X ̅: 38.77; males = 50) referred for outpatient neuropsychological evaluation. Pearson’s correlation coefficient assessed the relationship between the initial 15-second FAS interval and the total raw score. Results The Pearson correlation coefficient shows a moderate positive correlation between the 15 second interval for the letter F and FAS total score (r = 0.435). Further, this correlation is significant, (p < 0.001). Conclusions The study suggests that the initial 15-second FAS interval effectively predicts overall performance across pediatric and adult populations. This underscores the potential for a short-form Letter Fluency component as a valuable addition to clinical assessments. Short forms could alleviate patient frustration and maintain motivation during testing, enhancing the utility of cognitive measures like the D-KEFS FAS in clinical settings.