Operations and supply chain management scholars have recently focused on humanitarian disaster response activities. However, much of that research has dealt with disaster preparedness, decision-making, and logistics aspects of response efforts. So far, practices related to interorganizational interaction have received limited attention. In this article, we develop a theoretical framework of interaction-related humanitarian operations practices through a grounded theory building study conducted in the context of a major U.S. disaster, Hurricane Sandy. Our investigation identifies several novel practices that have not seen much research focus previously. Our findings advance humanitarian operations research and theory, as well as provide practical takeaways for organizations operating in disaster contexts.