This up-to-date text clearly presents a multitude of variables that poyentially affect the results of neuropsychological tests. Following a general discussion of neuropsychological constructs known to impact performance on neuropsychological tests: demographics, personality and sociocultural factors, all chapter authors, experts in their respective fields, present an empirical approach to assessment. They focus on the disorders under discussion (not solely the test that might be used in diagnosis), and reflect the contributions the field has made to detecting differences in disorders that have neurological underpinnings. Topics discussed are: Dementia, HIV - related syndromes, adult seizure… disorders, toxic exposure, mild to severe braininjury, and chronic fatigue syndrome.