An overview of the development of a computerized version of the Differential Aptitude Tests (DAT) is presented. It describes the previously existing printed version of the DAT, design of the computerized adaptive edition, calibration of the test items for use in the computerized version, and two field studies that compared the Adaptive and paper-and-pencil DATs to assess the reliability and validity of the adaptive edition. The DAT consists of seven power tests (Verbal Reasoning, Numerical Ability, Abstract Reasoning, Mechanical Reasoning, Space Relations, Spelling, and Language Usage) and one speeded test (Clerical Speed and Ability, CSA). The computerized edition, designed for use on the Apple II series, is half the length of the printed edition. Items were selected for the adaptive edition using a three-parameter item-response model, as well as the Rasch model. Results of the field tests showed that correlations between printed and computer editions were .78 to .88 on all seven power tests but .33 on the speeded test (CSA). No attempt was made to equate the adaptive CSA test with the printed one because of this low correlation. Factor loadings were found to be similar. It was concluded that the power tests could be considered psychometrically equivalent to their printed counterparts. (JGL)