Twenty-nine normal young men were administered the Halstead Battery and two additional tests commonly employed by neuropsychologists and were re-examined by the same instruments 20 weeks later. The results indicate that for our sample of normalSs the classification of an individual as “normal” by the Halstead Impairment Index is a clinical judgment with a very high degree of reliability. Data from two comparison groups (patients with cerebrovascular disease and patients with chronic schizophrenia) lent support to this conclusion. A similar study with other samples of normalSs as well as other better defined and matched psychiatric and brain-damagedSs is needed both to cross-validate and to extend this finding in order to increase the practicing clinician's confidence in his interpretation of an obtained value falling in thenormalrange for a given individual. Clinical neuropsychology is rapidly developing to the point that such validity (clinical reliability) for such individual judgments is no longer a hope but an increasingly more probable expectation.