Tackling grand challenges demands collaboration between public and private organizations to develop sustainable innovations. Yet, the frequent failures of public-private innovation partnerships (PPIPs) expose their inherent tensions and governance complexities. To address this issue, we study nine cases of PPIPs pursuing sustainability goals. Drawing on faultline theory, our analysis of 55 interviews and 167 pieces of secondary data reveals five distinct instruments that organizations emergently employed during the collaboration to bridge the public-private faultline. Besides pointing to the potential of these faultline-bridging instruments to foster alignment, this study also raises awareness of their potential to spark unintended consequences—such as igniting dormant faultlines within public and private subgroups and reshaping the collaborative dynamics. Subsequent adaptations of the faultline-bridging efforts can accommodate these unintended consequences. This study offers insights into PPIPs for grand challenges by challenging the predominant static views on their governance. It emphasizes the need for adaptability in managing the interplay of inter-organizational faultlines and the efforts to bridge them. We contribute to the literature on public-private collaboration for grand challenges, governance research, and faultline theory. Moreover, we seek to equip practitioners with tools to navigate the intricate tensions of cross-sector collaboration.
