This thesis is based on an ethnographic investigation of concepts related to mental health and madness among the Yolŋu peoples of north-east Arnhem Land, with a particular focus on Elcho Island and its main settlement, Galiwin‘ku. Over the past decade, there has been a proliferation of medically oriented research and mental health intervention programs in Indigenous health. Most of these refer to the principle that ‗culture‘ must play a fundamental role in Indigenous health care. However, lack of in-depth investigations about Indigenous knowledge related to health indicates that this principle plays only a nominal role in the implementation of these programs and has not resulted in a rethinking of basic assumptions guiding mental health services. The ethnographic research which informs this thesis started from the assumption that all societies around the world have developed ideas of ‗madness‘ or ‗abnormality‘, but that these are not necessarily understood in terms of ‗health‘ or ‗illness‘. Accordingly, the fieldwork focused on Yolŋu concepts related to ‗madness‘: what are the signs indicating mental or emotional problems? What causes madness? What are the responses of the ‗normal‘ members of society? What kinds of issues are elicited by the encounter with Western psychiatry? What are the self-representations of the ‗mad‘ person? The ethnography demonstrated the existence of an articulated body of knowledge related to ‗mental illness‘, although not one fashioned in medical terms. Understanding Yolŋu reflections about madness clearly involved embracing wider categories of life, person and relationships which their stories convey. The aim of this thesis is not to provide material for cross-cultural comparison between a Western and an Indigenous medical system but to clarify the relationship between Yolŋu conceptualizations of the world, person and relationships and Yolŋu representations of illness and healing. The work adds to understanding of some issues in the anthropological literature about healing and illness in Yolŋu society.