In connection with the development of item pools for the Navy's experimental Computerized Adaptive Testing (CAT) system, items in five different content areas (General Science, Paragraph Composition, Word Knowledge, Math Knowledge, and Arithmetic Reasoning) have been calibrated using item response theory (IRT) methodology. Operational Armed Services Vocational Aptitude Battery (ASVAB) subtests 8, 9, and 10 were calibrated with the new CAT items to insure that all estimated parameters in a content area were expressed relative to a common metric. The computer program LOGIST was used to fit the 3-parameter logistic model to the available item response data. Modifications to version 2.B of this program were made prior to completing the calibrations. These modifications were tested and found to improve the parameter estimates generated by LOGIST. In each content area, all CAT items and ASVAB items were calibrated simultaneously in a single LOGIST run. The median values of the estimated IRT parameters, obtained in each content area, suggest that CAT procedures will function quite effectively in each of these five content areas. Items in four more content areas, as well as additional items will be calibrated to augment three of the previously developed item banks. (PN)