This thesis examines Tibetan perspectives on the causation, management and treatment of mental illness (Tib.: sems nad) within a Tibetan exile community in Darjeeling, northeast India. Based on two six-month periods of ethnographic fieldwork conducted in 2011 and 2012, it examines common cultural understandings of mental illness and healing, and how these are reflected in health-seeking behaviour. To date, research on lay Tibetan perspectives of mental illness and their impact on health-seeking behaviour has been limited, especially in relation to the concept of smyo nad (‘madness’). Following on from work by Jacobson (2000, 2002, 2007) and Millard (2007), the thesis investigates lay Tibetan perceptions of the causation and treatment of various kinds of mental disorders through the use of indepth semi-structured interviews and participant observation, comparing and contrasting Tibetan approaches to those of biomedical psychology and psychiatry and their accompanying classification systems, the American Diagnostic and Statistical Manual of Mental Disorders (DSM) and European International Classification of Disease (ICD). Four case studies of individuals labelled with different Tibetan and biomedical diagnoses related to mental health conditions are described in order to illustrate a number of key concepts in Tibetan approaches to mental illness and its healing. The research found that that a number of informants successfully combined different – sometimes opposing – explanatory frameworks and treatment approaches in response to an episode of mental illness. However, the thesis concludes that the Tibetan and biomedical categories remain difficult to correlate, due in part to their culturally-specific nature, based on significantly different underlying assumptions regarding individuals and their relationship to the environment.