A computer adaptive test (CAT) is a delivery methodology that serves the larger goals of the assessment system in which it is embedded. A thorough analysis of the assessment system for which a CAT is being designed is critical to ensure that the delivery platform is appropriate and addresses all relevant complexities. As such, a CAT engine must be designed to conform to the validity and reliability of the overall system. This design takes the form of adherence to the assessment goals and objectives of the adaptive assessment system. When the assessment is adapted for use in another country, consideration must be given to any necessary revisions including content differences. This article addresses these considerations while drawing, in part, on the process followed in the development of the CAT delivery system designed to test English language workplace skills for the Singapore Workforce Development Agency. Topics include item creation and selection, calibration of the item pool, analysis and testing of the psychometric properties, and reporting and interpretation of scores. The characteristics and benefits of the CAT delivery system are detailed as well as implications for testing programs considering the use of a CAT delivery system. (Contains 2 figures.)