An inquiry attempted to build an agenda for research that would result in a cognitive theory of instruction capable of informing educational practice and extending the limits of knowledge about how people learn and develop. What would such a theory look like, how close are we to having one, and what directions must be followed to further its development are among the questions explored. A brief history is presented of psychological theories of instruction from the viewpoints of E. L. Thorndike, B. F. Skinner, Gestalt psychology, and Piaget. It is pointed out that a cognitive theory of instruction must be both descriptive (explaining why instruction works and why it does not) and prescriptive (suggesting what to do next time for better results). Within this framework, three components of such a theory of instruction are described and analyzed: (1) specification of capabilities to be acquired; (2) description of the acquisition processes; and (3) principles of intervention. (JD)