This document is the first comprehensive assessment of the Hindu Kush Himalaya (HKH) region. It comprises important scientific research on the social, economic, and environmental pillars of sustainable mountain development and will serve as a basis for evidence-based decision-making to safeguard the environment and advance people’s well-being. The compiled content is based on the collective knowledge of over 300 leading researchers, experts and policymakers, brought together by the Hindu Kush Himalayan Monitoring and Assessment Programme (HIMAP) under the coordination of the International Centre for Integrated Mountain Development (ICIMOD). This assessment (conducted between 2013 and 2017), comprehensively assesses the current state of knowledge of the HKH region, increases the understanding of various drivers of change and their impacts, addresses critical data gaps and develops a set of evidence-based and actionable policy solutions and recommendations. These are linked to nine mountain priorities for the mountains and people of the HKH consistent with the Sustainable Development Goals. This book is aimed at policy makers, academics and students interested in this important region and hopes to be a useful resource for contributors to global assessments such as the IPCC reports.