Book excerpt: This book is the result of the first global conference on mountain biodiversity, and is a contribution to the International Year of Mountains, 2002. The Global Mountain Biodiversity Assessment program is a Special Target Area Region project of DIVERSITAS (UNESCO and UNEP). Biological diversity is essential for the integrity of mountain ecosystems and this dependency is likely to increase as environmental (climate) and social conditions change. Steep terrain and climate, and severe land-use pressure cause mountain ecosystems to rank among the world's most endangered landscapes. The 28 chapters in this book represent research on the biological riches in all major mountain ranges of the world, and synthesize existing knowledge on mountain biodiversity - from diversity of bacteria, plants and animals to human diversity. The book is divided into five sections: an introduction providing an overview of the issues; plant and animal diversity; climate change and mountain biodiversity; land use and conservation; and a synthesis.