In an adaptive test, the test administrator chooses test items sequentially during the test, in such a way as to adapt test difficulty to examinee ability as shown during testing. An effectively designed adaptive test can resolve the dilemma inherent in conventional test design. By tailoring tests to individuals, the adaptive test can approximately achieve the high point precision of a peaked test and can extend that high level of precision over the wide range of a uniform test. As a result, a well-constructed adaptive test should be more broadly applicable than a conventional test of comparable item quality and test length, since its precision characteristics make it useful for classification about one or many cutting points, as well as for measurement over a wide range. This paper defines adaptive mental testing in relation to conventional mental testing, outlines the major research issues in adaptive mental testing, and reviews the state of the art for each of the research issues. The research issues are: (1) psychometric theory; (2) design of adaptive tests; (3) scoring adaptive tests; (4) the testing medium; (5) item pool development; and (6) advances in measurement technology. (Author/RL)