Wild grizzly bears, conducting their affairs undisturbed, are the essence of the wilderness spirit. Much has been written, both fact and fiction, about these awesome animals, but until very recently we have known little about the details of their daily existence. For twenty-five years, Adolph Murie, one of North America's greatest naturalists, spent his summers in Mount McKinley National Park (since renamed Denali National Park) tracking, recording, and interpreting the lives of these magnificent animals in one of their few remaining strongholds. Murie observed the grizzlies as they moved throughout their range. He noted how families were formed, how they found food, and he described in detail how they related to other animals with whom they came in contact, including man. Often he followed a bear family for days as it traveled through the park. Even though their behavior could be quite unpredictable, Murie was able to distinguish, through careful observation, the individuals who made up many distinct families.