Although the study of learning theory can produce principles applicable to the design of instruction, virtually no instructional materials in existence today have deliberately been prepared on the basis of such principles. Terms used in four different learning theories--motivation, (Neal Miller); stimulus control (Skinner); distinctive conditions and cumulative learning (Gagne); and subsumption (Ausubel)--suggest specific principles of learning. A general principle emerging from modern learning studies is that learning is an individual matter, in which essential idiosyncratic elements must be supplied by the learner himself. In applying these principles to the choice and use of media, an analysis of the events of instruction is required. These involve gaining and controlling attention; stimulating recall; guiding or cueing the learning; providing feedback; arranging for remembering; and assessing the final outcomes. No single medium is likely to be best fitted to perform all of these various functions. An arrangement involving combinations of media may hold the key to effective instruction and efficient media use, particularly where the individual establishes a large part of the learning conditions for himself. (PM)