Objective: Anxiety disorders are the most prevalent psychiatric disorders experienced by individuals in the United States, and anxiety is often assessed with anxiety symptom inventories. At present, though, there are no anxiety symptom inventories that include symptom validity indices. The present study sought to develop a symptom validity index for the most commonly used anxiety symptom inventory in neuropsychological practice, the Beck Anxiety Inventory (BAI). Method: A sample of 244 veterans seeking outpatient neuropsychological assessments were included in the study. Participants were divided into valid and invalid groups based on external criterion symptom validity tests. The valid participants were then divided into clinical subgroups (Current Anxiety, Lifetime Anxiety, and No Anxiety). A validity index derived from the BAI total score was examined for the total sample and all subgroups. Results: A cutoff of ≥ 29 was identified when utilizing the Valid Full Sample, which resulted in a 0.91 specificity rate and 0.54 sensitivity rate. However, cutoffs had to be adjusted when applied to the clinical subgroups. The Valid Current Anxiety subgroup required the largest cutoff increase (i.e. ≥ 36), which resulted in a 0.91 specificity rate and a 0.42 sensitivity rate. Conclusions: This is the first published article to develop a symptom validity index for the BAI. To minimize false positive errors, a BAI total score of ≥ 36 is recommended. © 2024 Informa UK Limited, trading as Taylor & Francis Group.