Terrorist attacks on U.S. chemical facilities could damage public health and the economy. While the Environmental Protection Agency (EPA) formerly led federal efforts to ensure chemical facility security, the Department of Homeland Security (DHS) is now the lead federal agency coordinating efforts to protect these facilities from terrorist attacks. GAO reviewed (1) DHS's actions to develop a strategy to protect the chemical industry, (2) DHS's actions to assist in the industry's security efforts and coordinate with EPA, (3) industry security initiatives and challenges, and (4) DHS's authorities and whether additional legislation is needed to ensure chemical plant security. GAO interviewed DHS, EPA, and industry officials, among others.