This Repository collects 11 best practices for cooperation between the civilian and defence cybersecurity sectors across the European Union, through a structured process of desk research, stakeholder consultation and expert validation. It is designed for policy makers, practitioners and researchers who need transferable, evidence-based models to strengthen civil-defence cooperation. Each practice is validated through the COcyber D4.1 methodology and tagged against the 8 cooperation needs identified in Deliverable D2.2. The full report is available as Deliverable D4.1 on Zenodo.