There is considerable evidence to show that computerized-adaptive testing (CAT) and multi-stage testing (MST) are viable frameworks for testing. With many testing organizations looking to move towards CAT or MST, it is important to know what framework is superior in different situations and at what cost in terms of measurement. What was needed is a comparison of the different testing procedures under various realistic testing conditions. This dissertation addressed the important problem of the increase or decrease in accuracy of ability estimation in using MST rather than CAT. The purpose of this study was to compare the accuracy of ability estimates produced by MST and CAT while keeping some variables fixed and varying others. A simulation study was conducted to investigate the effects of several factors on the accuracy of ability estimation using different CAT and MST designs. The factors that were manipulated are the number of stages, the number of subtests per stage, and the number of items per subtest. Kept constant were test length, distribution of subtest information, method of determining cut-points on subtests, amount of overlap between subtests, and method of scoring total test. The primary question of interest was, given a fixed test length, how many stages and many subtests per stage should there be to maximize measurement precision? Furthermore, how many items should there be in each subtest? Should there be more in the routing test or should there be more in the higher stage tests? Results showed that, in general, increasing the number of stages from two to three decreased the amount of errors in ability estimation. Increasing the number of subtests from three to five increased the accuracy of ability estimates as well as the efficiency of the MST designs relative to the P&P and CAT designs at most ability levels (-.75 to 2.25). Finally, at most ability levels (-.75 to 2.25), varying the number of items per stage had little effect on either the resulting accuracy of ability estimates or the relative efficiency of the MST designs to the P&P and CAT designs. (PsycINFO Database Record (c) 2003 APA, all rights reserved).