Abstract This paper is concerned with the purpose and form of representations of strategic knowledge in design. A number of issues concerning the role of representations in design are considered. A distinction is made between representations for describing design and representations for guiding or prescribing design. Issues about the role and form of representations `of' and `for' design are considered in the light of experience from a case study of vehicle engineering design. The goals of the project from which this work arises were two-fold: first, to identify examples of strategic knowledge from a domain expert; and second, to inform the computer support design field about that issue. The approach adopted was to gather empirical information and model the results using different analysis frameworks. Three types of representations are described: a domain model of strategic knowledge for supporting interactive system design, a model for representing strategic knowledge computationally, and a design process model of strategic knowledge in engineering design.