Many transactions in the business-to-business-field are governed on a relational basis. In such long-term business relationships, the object of exchange is but one determinant of relationship success. Soft factors such as the customer-directed behaviors a supplier demonstrates are generally believed to be a major determinant of performance variables. Based on the relational exchange framework, this paper examines the impact of relational behaviors on relationship quality in professional service relationships. An empirical study conducted among 206 purchasers of market research information provides evidence that supplier behaviors such as role integrity, flexibility, or solidarity have an important impact on different dimensions of customer-perceived relationship quality (satisfaction, trust, and commitment).