In this paper, we examine the suggested link between product architecture (i.e., the extent to which a product is modular vs. integral) and supply chain configuration (i.e., whether the product development is done internally by the manufacturer in an integrated supply chain or in collaboration with a supplier in a decentralized supply chain). Our model suggests that the choice of product architecture depends on firm, market, and product characteristics in addition to supply chain structure. In contrast to other studies, we find that the optimal mapping from architecture to supply chain structure is not always one-to-one. A decentralized supply chain may be associated with a more integral product when the technical collaboration penalty is not excessive and suppliers have significantly superior product development capabilities. Furthermore, in a decentralized supply chain, the nature of the relationship between the original equipment manufacturer and its supplier (adversarial or collaborative) plays a role in the choice of product architecture: modular architectures are more likely when the parties have adversarial relationships, while long-term trust-based relationships facilitate more integral product architectures.