The overall objective of this research was to explore the association between implemtation of cooperation purchasing/supplier relationship, internal service quality, and an organization's ability to provide quality products and services to its customers. Specifically, purchasing-related factors influencing internal and external product and service quality were identified from the literature and an internal service quality model was developed and then tested using empirical data. Survey data were collected from 118 US purchasing executives in a wide range of industries. The findings from this study indicate the existence of strong positive relationship between implematation of cooperative purchasing/supplier relationship, internal service quality, and the service and product quality provided to external customers. Additionally, the key role of purchasing in the integration and communication of quality expectations and quality performance throughout the firm is demonstrated.