Objective: Reliable Digit Span (RDS) has been shown to be an effective tool in identifying performance validity during neuropsychological test administration when calculated on the Weschler Adult Intelligence Scale – III (WAIS-III). The purpose of the current study was to examine the utility of RDS within the Neuropsychological Assessment Battery (NAB). Method: We performed a retrospective chart review of 125 active duty Army Soldiers referred for neurocognitive screening with a remote history of mTBI. Performance validity was determined via standard cut-scores on The Medical Symptom Validity Test (MSVT). In addition to sensitivity and specificity values, positive and negative predictive powers (PPP; NPP) were calculated at each proposed NAB RDS cut-off score. Results: NAB RDS ≤6 demonstrated the optimal cut score to invalid performance, with specificity of 85.7%, sensitivity of 20.6%, PPP of 35 and NPP of 74. Conclusion: NAB RDS classification accuracy appears to be consistent with WAIS-III RDS classification characteristics. Given the high specificity, scores ≤6 strongly indicate suboptimal effort in an mTBI population. However, as the NAB RDS demonstrated relatively low sensitivity, the concurrent administration of additional measures of performance validity is recommended. The views expressed in this abstract are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the US Government.