During the past 35 years the author's field investigations have covered much of the Pacific Coast of North America between Point Barrow and Lower California. Studies have been made of the animal life in practically all of our western national parks. The photographs and data in this publication are based largely upon this lengthy field experience. It has been impossible to photograph or even to mention briefly all of the several hundred species of birds and mammals found in all of the western national parks and monuments, so I have endeavored to select and to present a few representatives of the outstanding or characteristic species found in some of these areas. The list of both park areas and animals is necessarily incomplete. I have been asked repeatedly by park visitors what kinds of animals would most likely be found in a given national park. For their convenience, the various species of animals are listed according to the scientific classification, using common names, followed by a list of the principal western parks and monuments in which the creatures may be found. As here used, the term "species" includes all its subspecies. Thus, all geographic races of the black bear are grouped under the one heading: Black Bear.