UNESCO Biosphere Reserves (BRs) are designated areas in geographical regions of global socio-ecological significance. This definitive book shows their global relevance and contribution to environmental protection, biocultural diversity and education. Initiated in the 1970s as part of UNESCO’s Man and Biosphere (MAB) Programme, BRs share a set of common objectives, to support and demonstrate a balance between biodiversity conservation, sustainable development and research. The world’s 701 BRs form an international, intergovernmental network to support the aims of sustainability science, but this purpose has not always been widely understood. In three distinct sections, the book starts by outlining the origins of BRs and the MAB Programme, showing how they contribute to advancing sustainable development. The second section documents the evolution of BRs around the world, including case studies from each of the five UNESCO world regions. Each case study demonstrates how conservation, sustainable development and the role of scientific research have been interpreted locally. The book concludes by discussing thematic lessons to help understand the challenges and opportunities associated with sustainability science, providing a unique platform from which lessons can be learned. This includes how concepts become actions on the ground and how ideas can be taken up across sites at differing scales. This book will be of great interest to professionals engaged in conservation and sustainable development, NGOs, policy-makers and advanced students in environmental management, ecology, sustainability science, environmental anthropology and geography.