The bibliography of scientific work done in Yosemite National Park since World War I is too extensive to be included here. A goodly part of it is contained in _A Bibliography of National Parks and Monuments West of the Mississippi River_. References to research projects published since the appearance of that bibliography appear in the publications of the Yosemite Natural History Association, particularly the monthly journal, _Yosemite Nature Notes_. Especially significant items dealing with wildlife policy and trends in park management are included in the references appended to the present volume. In brief, it may be said that the wildlife problems of Yosemite National Park are now fairly well defined and that administrative and technical practices are so aligned as to assure preservation of the faunal and floral characteristics of the reservation within the concept of “public enjoyment and use” of today and tomorrow. As Director of the National Park Service, Newton B. Drury has said, “It is national park policy to display wildlife in a natural manner. The normal habits of animals are interfered with as little as possible, and artificial management is refrained from except for protective purposes and then only as a last resort. The pauperizing or domestication of the native animals is avoided, as is also the herding or feeding of these animals to provide ‘shows.’ Under this policy the park is a wildlife refuge but it is neither a circus or a zoo.” The wildlife of Yosemite, like its forests and wildflower displays, its renowned cliffs and waterfalls, its glacial pavements, its meadows and valleys, and its spectacular mountaintops, has enthralled its lay visitors quite as it has galvanized the scientist and technician. When Stephen T. Mather assumed the directorship of the national parks in 1916, he determined at the outset to provide park visitors with the information on the natural and historic features which they wanted. Educational endeavors were made a part of his projected program even before a staff had been organized. Surveys of outdoor educational methods and nature teaching as practiced in several European countries had been made in 1915 by C. M. Goethe, and his reports of the success of this work had inspired a few Americans to establish similar educational work in the United States. The California Fish and Game Commission in 1918 sent its educational director, Dr. Harold C. Bryant, into the Sierra to reach vacationists with the message of the conservationist. Yosemite National Park and the playground areas about Lake Tahoe witnessed the introduction of “nature guiding” several years prior to the inclusion of the work in the broad field program of the National Park Service.