This paper is the final report of a multi-year project sponsored by the Office of Naval Research (ONR) in 1987 through 1990. The main objectives of the research summarized were to: investigate the non-parametric approach to the estimation of the operating characteristics of discrete item responses; revise and strengthen the package computer programs and implement them in the Unix Operating System; investigate computerized adaptive testing procedure and use it in the SUN microcomputer system networked with personal computers; investigate multidimensional latent trait theory; and study item validity and test validity using the multidimensional latent space. Products published or presented during the research period included: five research reports through the ONR; a special contribution paper, "Comprehensive Latent Trait Theory"; 13 papers presented at conferences; and other seminars and research collaborations. This report reviews: (1) backgrounds and basic concepts used throughout the research; (2) two formulae for modification of the test information function; (3) the reliability coefficient and standard error of measurement in classical test theory in the context of latent trait models; (4) validity measures in the context of latent trait models; (5) the non-parametric approach to estimation of the operating characteristics of discrete item responses; (6) content-based observation of informative distractors and the efficiency of ability estimation; and (7) efficient computerized adaptive testing. Thirty graphs and five data tables are included. A 167-item distribution list is appended. (SLD)