The term multimedia used in this paper refers to different presentation media such as sound, graphics, text, etc. The possible benefits of a multimedia approach are discussed and some examples are given of how different media affect knowledge comprehension in human beings. An indication is given of what multimedia facilities are currently available. The PROMISE multimedia interface project is described, and in particular a possible approach to the formulation of a multimedia design methodology is proposed. Some initial guidelines on multimedia interface design are given. Although some of the ideas expressed here come from work in process control, they are likely to be generalizable to wider domains.