The Hindu Kush Himalaya (HKH), the highest mountain biome, also referred as the third pole or the water tower of Asia, is an important repository of biological and cultural diversities and source of varied ecosystems services to 240 million people living within and 1.9 billion in the mountains and downstream. The region has been in spotlight for being part of the 36 ‘Global Biodiversity Hotspot’ and ‘Crises Ecoregions’ as well as climate change hotspot. However, there is still knowledge gap on understanding the dynamics of changing landscapes and climate and its linkage to people, mostly challenged by poverty. International Centre for Integrated Mountain Development (ICIMOD), an intergovernmental regional knowledge and enabling centre, has been instrumental in developing better understanding on the dynamics of these fragile ecosystems and support its regional member countries through science-based integrated approaches. Since its inception, ICIMOD has been engaged in developing knowledge and supporting policies for mountain development focusing on socio-economic, ecological and environmental dimensions. In this chapter, we present the retrospect of our interventions in science, policy and practice in transboundary landscape management through regional cooperation mostly focused on biodiversity conservation and community development perspectives.