In 2023, following a review of a 2019 final rule that revised the regulations under the Endangered Species Act of 1973, as amended (Act), for adding and removing species from the Lists of Endangered and Threatened Wildlife and Plants (Lists) and designating critical habitat, the U.S. Fish and Wildlife Service and the National Marine Fisheries Service proposed to revise those regulations. The rulemaking process involved extensive stakeholder engagement, including a series of informational sessions to Federal and State agencies, federally recognized Tribes, Native Hawaiian and Pacific Islander community leaders, nongovernmental organizations, conservation partners, and industry groups. The final rule clarifies, interprets, and implements provisions under section 4 of the Act concerning the procedures and criteria used for listing, reclassifying, and delisting species on the Lists and designating critical habitat.