In the context of the Covid-19 pandemic, public officials are called on to implement different strategies in order to respond effectively. One of the lessons of emergency management research is that effective response is unikely without colaboration. Research on coilaborative emergency management has focused on measuring the effectiveness of intergovernmental and intersectoral relationships, but little is known about the performance of inter-jurisdictional collaboration. This paper seeks to measure the network effectiveness of intermunicipal self-organized response to Covid-19. It uses a network analysis approach to compare planned and actual emergency management networks operating in the Santiago Metropolitan Region of Chile. Content analysis of 202 formal agreements established by municpalites in 2009-2019 was used to capture the panned network. The actual network was depicted by collecting original data through an online survey that represented the 96% of the local governments located in this Latin American city. The results show a structural gap between planned and actual networks and reveal effectiveness problems associated with the disaster preparedness phase. However, an emergent intermunicipal network has supported collaborative response to the Covid-19 pandemic. The study provides lessons for policymakers, public managers and researchers in the coilaborative emergency management field.