This article introduces the theory behind and applications of adaptive personality assessment based on the item response theory. Two adaptive testing strategies were compared: (a) fixed test length and (b) clinical decision. Real-data simulations, based on the item responses from 1,000 subjects who had previously taken the 34-item Absorption scale (Tellegen, 1982) by means of paper-and-pencil format, were used to illustrate these strategies. Results suggest that computerized adaptive personality assessment works impressively well. With the fixed-test-length strategy, a 50% savings in administered items was achieved with little loss of measurement precision. In the clinical-decision testing strategy, individuals who were extreme on the Absorption trait were identified with perfect accuracy using, on average, 25% of the available items. The implications of these results for personality research and assessment are discussed.