Crisis events, including natural disasters, pandemics, and socio-political emergencies, demand rapid, coordinated responses from multiple organizations and sectors. Interagency collaboration and network governance have emerged as essential frameworks for effective crisis management. This theoretical paper explores the principles, mechanisms, and challenges of interagency collaboration in crises, drawing upon literature from public administration, organizational theory, and disaster management. Key elements include shared situational awareness, clear communication channels, joint decision-making, trust-building, and institutionalized coordination protocols. Network governance models facilitate cooperation across hierarchical and sectoral boundaries, enabling integrated responses that improve efficiency, resource allocation, and resilience. The paper also highlights barriers, including institutional silos, power asymmetries, and information-sharing constraints. Recommendations focus on building trust, standardizing procedures, leveraging technology, and fostering adaptive capacities to strengthen interagency coordination in complex crisis environments.