A computerized adaptive testing version of the Armed Services Vocational Aptitude Battery (CAT-ASVAB) is being developed to test ten areas of vocational aptitude. Development of the CAT-ASVAB is based upon the use of item banks, testing and scoring procedures, assessment of test reliability and test validity, a technical manual, and the development of equated scores for the paper-and-pencil and the CAT-ASVAB. There are three main considerations in the development of item pools: (1) content specifications--careful analysis of the content, skills, and knowledge comprising the aptitude area, and review of items; (2) item preparation, including consideration of the capabilities of the computer and its display, and psychometric standards as judged by experts; and (3) item calibration. The data collected for more than 2,000 test items on a military applicant sample provided item responses for over 2,000 examinees per item, for calibration purposes. The CAT-ASVAB battery uses the three parameter model, which assumes the concept of unidimensionality of each item. Future plans include the use of microcomputers for test administration, further work on the comparability of paper-and-pencil and computerized batteries, and the creation of a central testing facility. (GDC)