Purchasing operates at the interface between a company and its supply market environment. Its activities are essentially concerned with securing the resource inputs of materials, components and equipment into the business, and in the selection and handling of suppliers of those inputs. Many earlier studies have described and analysed buying decision‐making from a marketing perspective, in order to predict and influence the eventual sourcing decisions in a manner favourable to the supply company. For example, studies have identified the stages in buying, the roles and influence of individuals on buying decisions and the criteria used by buyers in choosing between alternative sources of supply. This has led to purchasing being viewed as a process in which the focus is primarily upon specific buying episodes or discrete purchasing decisions, such as the choice of new suppliers or the exercise of source loyalty to existing ones. An overall strategic view of the range of purchasing activities from the buyer's perspective has been neglected. Obviously, purchasing is not confined to isolated decisions and short‐term operational episodes. Indeed, recent work in the subject has emphasised that specific buying decisions are better viewed within the context of the overall relationships between buying and selling companies. Each supplier and customer is interested in the other's resources and capabilities. Consequently, the exchange of goods is but one part of a broader exchange of services, information and value systems between the two parties to a transaction. Clearly, buyers and sellers are active participants in the transaction process and are influenced by the actions of the other. Complex relationships develop between individual buyers and marketers in any dyadic interaction but they occur also between the members of the customer's decision‐making unit and a supplier's team of marketing; technical, manufacturing and managerial personnel. This “interaction approach” to industrial purchasing and marketing proposed by the IMP group of researchers, focuses attention upon the influence of four groups of variables on buyer‐seller relationships. First, the parties involved (individuals and organisations); second, the atmosphere surrounding the relationship (co‐operation, trust, exercise of power, dependence); third, the environmental context (market structure, competition), and fourth, the exchange process (the exchange of technological expertise, products, services, information etc).