How do buyer-supplier relationships affect innovation? This study suggests that the relational exchange norms of flexibility, information sharing, and solidarity (the bright side) encourage buyer innovation. However, negative (dark side) aspects of relationships with suppliers-loss of supplier objectivity, increasing buyer expectations, and supplier opportunism-may accompany the bright side and subsequently reduce buyer innovation. The study reports on the simultaneous effects of the bright and dark sides on innovation and the resultant effect on supplier performance as evaluated from the buyer's perspective. Using data from the travel and computer industry, regression models reveal that the bright side encourages buyer innovation. Buyers reciprocate this support by enhancing their supplier evaluations. The findings indicate that rising buyer expectations-supposedly a dark side of relational exchange-encourage innovation, while loss of supplier objectivity reduces relationship performance. These findings imply that the bright and dark sides are not mutually exclusive dimensions of good versus bad behavior. © 2011 Elsevier Inc.