A computer-assisted instruction (CAl) system which includes facilities for interactive graphics and for limited natural language processing has been implemented on a DEC PDP-ll minicomputer. Lesson authoring aids permit inexperiencedauthors to create lessons with ease and permit transporting lessons to and from other systems. The system supports eight simultaneous independent users and provides facilities for student performance evaluation and record management. AVID (an acronym for Academic and VocationalInteractive Dialog) is a general-purpose system for Computer-Assisted Instruction (CAl) implemented on the Digital Equipment Corporation (DEC) PDP-II under the RT-11 operating system. Although AVID was developed in a medical environment, it has been designed for application to a wide range of academic or vocational education needs. The system design has been directed toward three primary goals: to provide maximum responsiveness to student needs, permit lesson development by inexperienced authors, and keep hardware costs to a minimum.Responsiveness to student needs is provided by a natural language question-answering facility. The facility permits a student to enter a query as a simple English question in order to locate curricular material located anywhere in the system's data base. Lesson development is eased by providing an authoring option in which the dialogue is system driven (e.g., the entry of each component of the lesson is prompted). This facility permits a content-area expert with little or no computer experience to generate quality lessons with a minimum of training. CAl system costs are kept to a minimum by designing AVID to run on a small minicomputer rather than timesharing on a full-sized computer . AVID could service several terminals on a system as small as a