A plan for a long term tracking system for handicapped children (birth to 5 years old) in Illinois is considered. The plan, based on agreements among five state agencies, could be used in a variety of ways, including for direct client care, statistical recordkeeping, and service evaluation. Advantages of an interactive system are identified, and the important elements of interagency agreements on such topics as data storage and processing are emphasized. Equipment needs and personnel requirements are considered, along with security measures to safeguard confidentiality. (CL)