Two men played a crucial role in the creation and early history of the National Park Service: Stephen T. Mather, a public relations genius of sweeping vision, and Horace M. Albright, an able lawyer and administrator who helped transform that vision into reality. In Creating the National Park Service, Albright and his daughter, Marian Albright Schenck, reveal the previously untold story of the critical "missing years" in the history of the service. During this period, 1917 and 1918, Mather's problems with manic depression were kept hidden from public view, and Albright, his able and devoted assistant, served as acting director and assumed Mather's responsibilities. Albright played a decisive part in the passage of the National Park Service Organic Act of 1916; the formulation of principles and policies for management of the parks; the defense of the parks against exploitation by ranchers, lumber companies, and mining interests during World War I; and other issues crucial to the future of the fledgling park system.