Computerized Clinical Simulation Testing (CST®) is under research and development by the National Council of State Boards of Nursing for potential use as a component of the National Council Licensure Examination for Registered Nurses. This interactive software permits the realistic assessment and management of client needs through free-text entry of requests for nursing activities. Implementation of each nursing activity elicits a realistic client response. A major component of the system is a default client response database that incorporates responses for 38 different client condition categories as well as rules for their automation. This article describes and illustrates the characteristics and complexity of this database that Is designed to assist in the portrayal of realistic client situations.