The Endangered Species Act is a landmark environmental law that was passed in 1973. The ESA is designed to protect and recover imperiled species and the ecosystems they depend on. It does this by requiring federal agencies to consult with the U.S. Fish and Wildlife Service or the National Marine Fisheries Service when any action they take may affect a listed species or its critical habitat. The ESA also establishes a process for listing species as threatened or endangered, and for developing and implementing recovery plans for these species.