The purpose of this study is to develop and test a customer defection model describing an organizational buyer’s propensity to stop purchasing from a supplier within a multisource buyer–seller relationship. A total of 168 employees who worked in purchasing using multiple suppliers in procurement were used for this study. Findings provide strategies for the salesperson to utilize in order to reduce the customer’s perception of available alternatives (e.g., increase trust in the salesperson) and defection (e.g., increase customer satisfaction and commitment). Findings also show that the relationship between satisfaction and commitment is fully mediated by trust within a multisource relationship.