The advantages of computerized adaptive testing are discussed, and an example illustrates its use in sixth grade mathematics. These tests are administered at a computer terminal, and the test items to be administered are selected according to the difficulty level appropriate to the individual's ability. Tailoring increases the psychometric efficiency of the test by providing the same precision as a traditional test, using half as many items. Scoring is immediate and the administration procedures are easily standardized. Five essential components are the test theory, item bank, strategy, delivery system, and research. The feasibility of the Computerized Adaptive Mathematics Locator (CAML) was studied in 137 California sixth-graders. This project was part of the development of the Comprehensive Assessment System, considered as a replacement for the California Assessment Program. From a 200-item mathematics item bank, each student was given a 30-item test on the school's microcomputer, generally an Apple II. Data analysis is not yet completed. Other potential applications include military personnel aptitude testing, large-scale basic skills or minimum competency testing, diagnosis, and placement testing. (GDC)