This is an ethnographic study of the Orang Rimba ('people of the forest'), a Malay-speaking minority group who traditionally lived throughout the lowland rainforests of Jambi, Sumatra. The Orang Rimba have much in common with surrounding Malay peoples, including a similar local dialect and variants of regional Malay customs and beliefs. They are different from the Malay and other Austronesian peoples in that they have a unique, mobile, flexible economy that traditionally shifts in and out of periods of swidden gardening and a very nomadic life based on digging for wild yams, largely upon death. They have an egalitarian social system based on sharing and reciprocity, which occurs within the context of a system of relationships in which women have great rights over forest resources and extraordinary distribution rights. They are also unique for their traditional non-Islamic religious beliefs, which they believe are crucial towards maintaining their way of life in the forest based on maintaining separation with the outside world. While the Makekal Orang Rimba believe themselves to share common origins with the Malay/Melayu, the downstream world of the villagers is perceived as a source of danger and sickness, which holds the potential to disrupt the delicate relations with their gods and make life in the forest impossible. ¶ Within the history of an unstable and assimilative upstream climate that was often hostile towards animist forest peoples, ethnic boundaries have served as a means to maintain their social identity, safety, and maintain a distinctive way of life in the forest. However, within the context of an egalitarian share society in which groupings of closely related women have a great deal of authority over the management and distribution of resources, including game, and the power of men is diminished through dispersed uxorilocal residence patterns, ethnic boundaries are also closely intertwined with internal power issues. The authority adult men is marked by their duty and obligation to protect and shield the rights of women from a dangerous outside world, and all outside males who are not immediate kin, through the manipulation of a convoluted system of law and fines paid in sheets of cloth. While females have great rights in their society, and the complete freedom to bully men through their passions and voice, their social mobility is limited by some of the most rigid gender divisions in all of Southeast Asia. Male authority is also marked within the domain of religion, through their duty to maintain the order and balance of their material and spiritual world (adat) in the forests by observing and enforcing religious prohibitions, which restrict relations with the outside world. This serves to facilitate close relations with their gods in matters ranging from health and subsistence to maintaining the timely occurrence of the seasonal fruits, honey, and migrations of bearded pigs. ¶ This thesis explores how the Orang Rimba maintain their distinct social identity as 'the people of the forest' through an examination of their customs, beliefs and religion (adat), and their belief and ritual surrounding fruits and the annual season of fruits, a primary season in the lowland dipterocarp forests of Sumatra. Throughout the thesis, I explore some of the key concepts, structural categories (forest-village, upstream-downstream, mobility-sedentism, hot-cold, and reason-passion), and metaphor that run through their system of beliefs and religion, and how some of these beliefs influence their social, moral and cosmological orders, relations amongst themselves, and with the outside world. A broader theme examines how religious beliefs are intertwined with social relations, which are largely based on issues of gender, adulthood, relations of affinity and male experience in the realms of law and religion, and how some of their beliefs are interrelated with maintaining ethnic boundaries with outsiders. Some of these topics are explored in their social relations, the structure of their origin stories, gender related food prohibitions, and the management of forest resources. These issues are examined in light of the great change that has taken place over the last 30 years, a result of large-scale logging, plantations and development projects.