With the Yellowstone River Valley of Montana as its setting, this book introduces readers to sustainability issues, theory, and science. Sustainability offers a vision for business and society that benefits Earth. Yet sustainability is often taught in abstract and disconnected ways. This book addresses business profitability, physical environment processes, wildlife, public policies, and American Indian rights. It stresses practical understandings of sustainability via detailed attention to the people of the valley. The case sets the stage for data gathering, analyses, and decision making. Readers will recognize similar concerns in other watersheds and understand sustainability anew.