The present study examined the contribution of tests that compose the Impairment Index with regard to their ability to predict brain impairment. The investigation further examines the ability of various other tests, chosen because of their observed usefulness in detecting brain impairment. Subjects composing the brain damaged group (n = 298) were found to be impaired on both CT and EEG examinations. The pseudo-neurological control group (n = 193) consisted of patients referred for testing yet all non-neuropsychological tests were normal. Discriminant analyses were conducted to determine the weightings of each test as well as to determine the overall prediction accuracies of three groupings of tests. These analyses demonstrate that tests, not comprising the Impairment Index, are of predictive value in determining dysfunction: Thurstone Word Fluency and a 60 minute delayed recall from the WMS. Overall prediction accuracies of the various test groupings ranged from 73.52% to 78.02%. No statistically significant reduction of accuracy resulted with cross validation. All tests of statistically predictive value and all prediction results with their corresponding discriminant formulas are reported as well as a discussion of the application of these findings.