The performance of a disaster response system is related to its capacity to facilitate interaction and situational awareness among the organizations that respond to a disaster event. In line with the assumption that formal institutions have an impact on the organization and performance of a country's disaster management system, governments around the world have sought to improve their disaster management capacities through the promulgation of laws and regulations. The literature, however, is limited in its ability to explain the effect that formal institutions have on the emergence of inter‐organizational interactions in disaster response contexts. This article explores how formal institutions, shaped by legal institutions and information technology, influenced inter‐organizational interactions after two disaster events in Taiwan: The ChiChi Earthquake in 1999 and Typhoon Morakot in 2009. Through a content analysis of newspaper articles and qualitative interviews with decision makers involved in these events, this study identifies how formal institutions facilitated and inhibited inter‐organizational interaction under uncertain and emergent situations. This study not only contributes to the development of institutional and disaster management theory, it also provides policymakers with insights into how to strengthen the capacity of their disaster management systems.