Computerized adaptive testing in personality assessment can improve efficiency by significantly reducing the number of items administered to answer an assessment question. Two approaches have been explored for adaptive testing in computerized personality assessment: item response theory and the countdown method. In this article, the authors review the literature on each and report the results of an investigation designed to explore the utility, in terms of item and time savings, and validity, in terms of correlations with external criterion measures, of an expanded countdown method-based research version of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), the MMPI-2 Computerized Adaptive Version (MMPI-2-CA). Participants were 433 undergraduate college students (170 men and 263 women). Results indicated considerable item savings and corresponding time savings for the adaptive testing modalities compared with a conventional computerized MMPI-2 administration. Furthermore, computerized adaptive administration yielded comparable results to computerized conventional administration of the MMPI-2 in terms of both test scores and their validity. Future directions for computerized adaptive personality testing are discussed.