A changed and deteriorated security situation demands a robust total defence capability. Crises rarely relate to a certain order, which requires that resources are used jointly across sector and organizational boundaries. Collaboration is considered a prerequisite for crisis management ability and total defence. This thesis examines the process of collaboration within total defence. By studying relational aspects of collaboration, the study shows the importance of trust for total defence. The study shows that factors that influence the collaboration process are based on factors that are driven by trust. Trust is crucial for a flexible and solution focused collaboration process and therefore important for total defence capability.