When the national park system was first established in 1916, the goal "to conserve unimpaired" seemed straightforward. But Robert Keiter argues that parks have always served a variety of competing purposes, from wildlife protection and scientific discovery to tourism and commercial development. In this trenchant analysis, he explains how parks must be managed more effectively to meet increasing demands in the face of climate, environmental, and demographic changes.  Taking a topical approach, Keiter traces the history of the national park idea from its inception to its uncertain future. Thematic chapters explore our changing conceptions of the parks as wilderness sanctuaries, playgrounds, educational facilities, and more. He also examines key controversies that have shaped the parks and our perception of them.  Ultimately, Keiter demonstrates that parks cannot be treated as special islands, but must be managed as the critical cores of larger ecosystems. Only when the National Park Service works with surrounding areas can the parks meet critical habitat, large-scale connectivity, clean air and water needs, and also provide sanctuaries where people can experience nature. Today's mandate must remain to conserve unimpaired-but Keiter shows how the national park idea can and must go much farther.  Professionals, students, and scholars with an interest in environmental history, national parks, and federal land management, as well as scientists and managers working on adaptation to climate change should find the book useful and inspiring.