An ongoing debate in marketing literature is whether market knowledge facilitates or impedes new product innovativeness. To reconcile inconsistent findings, this study disaggregates market knowledge into breadth and depth dimensions and uncovers their divergent effects on new product innovativeness. Given organizations' increasing reliance on network contacts for access to market knowledge, we focus on market knowledge derived from external ties. Based on an empirical test of 244 firms in China, this study finds that market knowledge breadth has a U-shaped relationship, whereas market knowledge depth has an inverted U-shaped relationship, with product innovativeness. These findings carry important theoretical and managerial implications. © 2011 Springer Science+Business Media, LLC.