Three and one-half years of research on computerized ability testing are summarized. The original objectives of the research were: (1) to develop and implement the stratified computer-based ability test; (2) to compare, on psychometric criteria, the various approaches to computer-based ability testing, including the stratified computerized test, the pyramidal approach, Lord's flexilevel test, two stage testing, and some mathematical models for computerized testing; (3) to determine the effect on ability test scores of maintaining test items at a level of difficulty near the individual's estimated ability level by means of computer controlled administration under one or more of the stated strategies; (4) providing feedback of correctness of response to each item within the standard models for computerized testing by using a special variation of the stratified approach designed to insure various proportions of correct responses; and (5) to determine the utility for diagnostic purposes of information on an individual's item response latencies. The research approach is summarized and related to the eighteen technical reports produced under this contract. Twenty-one major research findings are presented. The implications of the research findings and methods for future research in computerized adaptive testing are described. Also included are abstracts of the eighteen technical reports derived from this research. (Author/DEP)