ABSTRACT—Temperate grasslands are one of the world’s great biomes and were once home to some of the largest assemblages of wildlife the earth has ever known. Today these grasslands are considered the most altered terrestrial ecosystem on the planet and are recognized as the most endangered ecosystem on most continents. While species and habitat declines continue, temperate grasslands have the lowest level of protection of the world’s 14 biomes. With only 4% of the biome under protected status, considerable effort will be required to increase this level of protection. Several international bodies have suggested that achieving at least a 10% level of protection should be considered a minimum, yet this is a monumental challenge in an ecosystem now so vastly altered. This paper presents a global overview of the status of protected areas in the context of the health and extent of the world’s temperate grasslands and identifies the scope of remaining opportunities and regional priorities for increasing the level of protection. The Temperate Grasslands Conservation Initiative will facilitate international collaboration for, and develop a strategy to achieve, meaningful protection and sustainable use. The Northern Great Plains ecoregion is of international significance