Student achievement test scores were compared and equated, using three different testing methods: paper-administered, computer-administered, and computerized adaptive testing. The tests were developed from third and sixth grade mathematics item banks of the California Assessment Program. The paper and the computer-administered tests were identical in item content, format, and sequence. The computerized adaptive test consisted of an adaptive subset of the computer-administered test. A total of 575 students were administered two of the three types of tests in varying sequence. PLATO/WICAT System 300 computers were used to administer the tests. Although the paper and computer-administered tests contained 55 or 62 items, the adaptive test usually contained twenty items. Item response theory and analysis of variance were performed. Results supported the comparability of paper-administered and computer-administered tests. The computer-administered test required half to three-quarters as much testing time as the paper and pencil test; the adaptive test required one-fourth as much time as the paper and pencil test. Scores tended to be lower on the second test administered. Ability estimates for all three tests were highly correlated. Both the two- and the three-parameter item response theory model were suitable. Three pages of references are included. The two appendixes consist of: (1) comparisons of item parameters; and (2) test information and standard error curves. (GDC)