"In September, 2014, the National Marine Fisheries Service (NMFS) listed 15 Indo-Pacific coral species as 'threatened' under the U.S. Endangered Species Act. Many Indo-Pacific corals are quite difficult to identify to species, but identification is necessary for implementation of the listings. This guide is intended to help with identification of colonies of these species living on the coral reefs of U.S. Pacific areas, namely American Samoa, Guam, the Commonwealth of the Northern Marianas Islands, and the U.S Pacific Remote Island Areas (PRIA)...Here, we present a guide to the field identification of the ESA-listed, threatened corals of the U.S. Pacific. Species are presented in an order that groups similar corals together as much as possible, and will present more common or widespread species at the start. In addition, other similar species will be presented to highlight the differences between taxa"--Introduction.