In 2014, the United States in partnership with international organizations and nearly 30 partner countries launched the Global Health Security Agenda (GHSA) to accelerate progress to improve prevention, detection, and response capabilities for infectious disease outbreaks that can cause public health emergencies. Objective 9 of the GHSA calls for improved global access to medical countermeasures and establishes as a target the development of national policy frameworks for sending and receiving medical countermeasures from and to international partners during public health emergencies. The term medical countermeasures refers to vaccines, antimicrobials, therapeutics, and diagnostics that address the public health and medical consequences of chemical, biological, radiological, and nuclear events; pandemic influenza; and emerging infectious diseases. They are stockpiled by a few countries to protect their own populations and by international organizations, such as the World Health Organization (WHO), for the international community, typically for recipients with limited resources. However, as observed during the 2009 H1N1 influenza pandemic, legal, regulatory, logistical, and funding barriers slowed the ability of WHO and countries to quickly deploy or receive vaccine. Had the 2009 H1N1 influenza pandemic been more severe, the world would have been ill prepared to cope with the global demand for rapid access to medical countermeasures. This article summarizes the US government efforts to develop a national framework to deploy medical countermeasures internationally and a number of engagements to develop regional and international mechanisms, thus increasing global capacity to respond to public health emergencies.