This study investigates how multiple dimensions of power each facilitate knowledge integration within innovation projects in supply chains and their interrelationships. Adopting a process perspective of knowledge, we offer an alternative to much of the existing debate, which has focussed on the possession of resources. We collected data from four case-study Original Equipment Manufacturers and six associated suppliers and analysed these using Template Analysis and cross-case analysis. Our findings reveal how the power of the system, operationalized through relative performance measures, performance measurement mechanisms and the individuals in-charge of them, provides a facilitative context within which other dimensions of power operate. Here, the power of resources (expert and legitimate power), processes (associated with raising issues, cross-functional teams, early supplier involvement and reviews) and meaning (creating legitimacy through reviews) interact to support knowledge integration within innovation projects in supply chains. This, we argue, emphasises the plurality of power dimensions deployed and importance of their interrelationships in facilitating knowledge integration within hierarchical supply chain networks.