This chapter provides an overview of Himalayan forest classification and summarises a novel leaf-based classification system. The Himalayas, with their vast climatic and topographical diversity, host a complex mosaic of forest ecosystems primarily determined by elevation-dependent temperature gradients and precipitation patterns. Traditional classification systems have categorised Himalayan forests based on climatic factors, but these systems often struggle to capture the ecological nuances of mountainous vegetation. We propose a classification based on leaf traits—including leaf life span, phenology, form and sclerophylly—which offers greater ecological relevance. Himalayan forests are divided into five main types: evergreen with about one-year leaf lifespan (e1), tropical evergreen with mixed leaf lifespan (e2), coniferous with multi-year leaves (e3), winter deciduous (dw) and pre-monsoon deciduous (dp). Particularly distinctive are the e1 forests, characterised by simultaneous leaf drop and flush during pre-monsoon periods, which represent a uniquely Himalayan adaptation to monsoon-dominated climate patterns. A leaf-based classification system enables more effective remote sensing applications and provides insights into forest responses to climate change. The chapter also highlights how biogeographic factors create a fundamental division between the diverse Indo-Malayan forests of the eastern Himalayas and the simpler, often monodominant Palearctic-influenced forests of the western region.