Abstract
Cross-sector collaborations between public institutions are increasingly promoted as a mechanism to address complex societal challenges. Yet the conditions shaping their formation and development remain poorly understood. Existing collaborative governance theory tends to treat partner organisations as coherent actors. This neglects intra-organisational dynamics that spill over into inter-organisational processes. Drawing on longitudinal evidence from a university–NHS collaboration in England during a period of major health system reform, we identify four mechanisms through which intra-organisational fragmentation shapes collaborative governance trajectories: internal legitimacy erosion, professional resistance, leadership turnover, and resource contestation. These findings challenge the implicit assumption of organisational coherence in collaborative governance theory and advance a multi-level account of cross-sector collaboration in institutionalised public systems.