Buying centers and buying situations have an important influence on organizational purchasing. A buying center consists of a group of individuals who share common goals, risks, and knowledge important to a purchase decision. A buyer or purchasing manager is almost always a member of a buying center.

However, other individuals may affect organizational purchasing due to their unique roles in a purchase decision. Five specific roles that a person may play in a buying center include users, influencers, buyers, deciders, and gatekeepers. The specific buying situation will influence the number of people and the different roles played in a buying center. For a routine reorder of an item—a straight rebuy situation—a purchasing manager or buyer will typically act alone in making a purchasing decision. When an organization is a first-time purchaser of a product or service—a new buy situation—a buying center is enlarged and all five roles in a buying center often emerge. A modified rebuy situation lies between these two extremes. Figure 5–5 offers additional insights into how buying centers and buying situations influence organizational purchasing.