This article discusses the neuropsychological assessment of executive functions with respect to relevant clinical issues. Although neural mechanisms of executive dysfunction are postulated to involve the frontal lobes, the vital contribution of nonfrontal brain regions to executive abilities cannot be underestimated. A comprehensive neuropsychological testing approach, supplemented with keen observation of behavior outside the formal testing setting, is imperative in the determination of executive dysfunction. The development of clinically useful psychometric instruments in assessing executive functions is central to the evaluation of cognitive capabilities of individuals with a wide range of neuropsychiatric disorders. The clinician must also be aware of the limitations of "frontal" tests and take these limitations into consideration when addressing issues of assessment.