DHS is proposing to move foot-and mouth disease (FMD) research from its current location at the Plum Island Animal Disease Center–located on a federally owned island off the northern tip of Long Island, New York–and potentially onto the United States mainland. FMD is the most highly infectious animal disease that is known. Nearly 100 percent of exposed animals become infected. A single outbreak of FMD on the U.S. mainland could have significant economic consequences. Concerns have been raised about moving FMD research off its island location and onto the U.S. mainland–where it would be in closer proximity to susceptible animal populations–as opposed to building a new facility on the island. GAO was asked to evaluate the evidence DHS used to support its decision that FMD work can be done safely on the U.S. mainland, whether an island location provides any additional protection over and above that provided by modern high containment laboratories on the mainland, and the economic consequences of an FMD outbreak on the U.S. mainland. In preparing this testimony, GAO interviewed officials from DHS and USDA, talked with experts in FMD and high-containment laboratories worldwide, and reviewed studies on FMD, high-containment laboratories, and the economic consequences of FMD outbreaks. GAO also visited the Plum Island Animal Disease Center and other animal biocontainment laboratories in other countries.