A real-data simulation of computerized adaptive administration of the MMPI was conducted with data obtained from two personnel-selection samples and two clinical samples. A modification of the countdown method was tested to determine the usefulness, in terms of item administration savings, of several different test administration procedures. Substantial item administration savings were achieved for all four samples, though the clinical samples required administration of more items to achieve accurate classification and/or full-scale scores than did the personnel-selection samples. The use of normative item endorsement frequencies was found to be as effective as sample-specific frequencies for the determination of item administration order. The role of computerized adaptive testing in the future of personality assessment is discussed., (C) 1989 by the American Psychological Association