Although the number and importance of joint innovation projects between suppliers and their customers continue to rise, the literature has yet to resolve a key question: Do embedded ties with customers help or hurt supplier innovation? Drawing on both the tie strength and knowledge literatures, the authors theorize that embedded ties interact with supplier and customer innovation knowledge to influence supplier innovation. In a sample of 157 Dutch business-to-business innovation relationships, they observe that embedded ties weaken how much suppliers benefit from customer innovation knowledge because of worries about customer opportunism (the dark side of embedded ties). However, they uncover three moderating relationship and governance features that allow suppliers to overcome these dark-side effects and even increase innovation (the bright side of embedded ties). Finally, although the authors predicted a bright-side effect, they find that embedded ties neither help nor hinder the supplier to leverage its own innovation knowledge in the relationship. © 2011, American Marketing Association.