As model regions for balancing ecological with economic and social needs, biosphere reserves, by involving local stakeholders, are intended to test and develop future-oriented solutions for today's challenges in mountain regions, such as food security, poverty reduction, erosion, global warming and the conservation of biodiversity. However, the challenging task of implementing UNESCO's Man and the Biosphere Reserve concept in an ideal manner may be a little over-ambitious. The reality sometimes shows a different picture. In this publication you will find various examples - good and critical ones - of mountain biosphere reserves from all over the world and read about the important roles they play as sites for conserving biodiversity, for international science collaboration, and for enhancing the sustainable use of natural resources.