A new conception of computer-based instructional systems is presented in this design of a system that can deliver individualized information sequences not only to learners and trainees, but to reference workers, reviewers, etc. Underlying the system is a flexible data base organized into labelled, movable information blocks according to the principles of "information mapping"-- a system for categorizing and displaying information. This report itself is written in modified information-mapping style. A significant feature of this computerized information service is that the control of information selection and arrangement can be assigned entirely to the user, entirely to the system, or to both in one of the many possible patterns of shared responsibility. When the system takes part in information-sequencing decisions, its many mechanisms for individualizing come into play. The executive program consults short-term and long-term data about the individual, his objectives, capabilities, interests, and present status before it selects and arranges blocks from the data base to display for him. Evaluation and feedback are also individualized. The system's capability for controlling conditions and recording user-system interactions make it suitable for research on individualization in education. (Author)