A Practice Note discussing the requirements of the Endangered Species Act (ESA) for developers of real estate, infrastructure, and other construction projects. This Note discusses the Act's prohibition against the "take" of threatened and endangered species, the ESA consultation process with the National Marine Fisheries Service or US Fish and Wildlife Service that may be required under the ESA, and the impact of the listing of new species on developers and owners of real property. It also discusses the designation of critical habitat under the ESA, citizen enforcement risks, and state endangered species laws.