This research program was designed to investigate the applications of item response theory and computerized adaptive testing to the unique problems of the measurement of ability and the measurement of achievement. The research utilized a combination of monte carlo simulation studies and live-testing studies. The research approach for adaptive achievement testing included: intersubtest branching; the dimensionality of measured achievement over time; adaptive mastery testing; and adaptive self-referenced testing. The research approach for adaptive ability testing included: adaptive testing strategies; and response modes, test item formats and effects of test administration variables. This research is summarized and related to ten technical reports and other publications. Abstracts of the technical reports are included and the major research findings are presented. (PN)