AbstractThis paper is offered as an operational research contribution to design methodology. The process of design is defined as a decision-making process where the total problem is divided into subproblems or levels of the process. Within each level, the stages of analysis, synthesis and evaluation are defined. Difficulties associated with the interdependence of decisions are described with reference to attempts of others to find systematic methods for assisting designers. The author shows that interdependence between decisions can be represented by a graph (collection of nodes and arcs) and a technique known as the analysis of interconnected decision-areas (AIDA) is introduced. AIDA can be used to determine the number of solutions and their form and, if criteria of choice are available, can be used to find optimal solutions. The use of AIDA is illustrated by an example drawn from the field of architecture and the paper concludes by indicating possible new areas where the technique may be applied.