Maritime security challenges have grown in frequency and complexity, thereby increasing the number of government agencies tasked with, or responsible for, identifying threats and responding. Governments have generally not sought to consolidate authorities within a single agency. Instead, some governments in the past decade have created frameworks that integrate agencies with separate chains of command, authorities, capabilities, and capacities. This “Whole-of-Government” approach in response to maritime security threats or incidents is a relatively new development in homeland/national security and is redefining how governments share information, collaborate, and respond to maritime threats. In this Chapter, we discuss the National-Level Maritime Threat Response Framework of the United States, reviewing the organizational structure and processes involved in coordination and information sharing, all to yield a single, networked response. We highlight the events of the US response to the hijacking of the M/V MAERSK ALABAMA to demonstrate the functioning of this Whole-of-Government approach. Likewise, we also discuss briefly the National-Level Maritime Threat Response Frameworks of several other governments.