The Rendille, Eastern Cushitic camel pastoralists, live in northern Kenya of East Africa. In this article, firstly, the age-system, the developmental cycle of the family, and the organization of subsistence group are analysed, and it is concluded that the age-system and the patrilineal descent group with higher political, economic, and residential corporateness play an important role in maintaining the pastoral subsistence of the Rendille. Secondarily, the Rendille age-system is compared with that of their neighboring pastoral peoples in terms of structure and function, and it is discussed that some modifications have been made in the three points: the period of enrollment into age-set, acceptance of climbing up to a higher age-set, and sapadi institution, on the age-system to meet the Rendille subsistence. The Rendille*l, numbering some 20,000 persons, are an Eastern-Cushitic population occupying an area of 50,000 km 2 in the arid lowland of northern Kenya. They cannot practice cultivation with their rudimentary technology in the lowlands where annual rainfall is less than 255 mm. Thus, they depend almost exclusively on nomadic pastoralism for their subsistence. The Rendilleland ( ili-Rendille ) extends from the eastern shore of Lake Turkana, in the west, eastwards to the main road linking Kenya and Ethiopia. The northern boundary is marked by the Chalbi Desert, and the southern by Baragoi, Wamba and Archer's Post. Most of this area lies at an elevation of 40Q-1200 m above sea level, with Mt. Marsabit ( 1707 m ) in the northeast, Mt. Kulal ( 2604 m ) and Mt. Nyru ( 2753 m ) in the west and Mt. Ndoto ( 2637 m ) and the Mathews Range ( 2376 m ) in the south. There is a gradual decrease in elevation east of the western highlands, in the vicinity of Mt. Kulal, Mt. Nyru and Mt. Ndoto. The lowland continues through Somaliland to the Indian coast. Rendilleland is located at the eastern edge of the Rift Valley, and a zone of black lava is prominent from the east shore of Lake Turkana to the foot of Mt. Marsabit. The Rendille raise mainly camels and small livestock ( goats and sheep ); subsidiarily a few cattle and donkeys. Of them, cattle and small livestock are used as cash animals for agricultural products, such as maize flour, but only in case of need. However, the Rendille do not rear livestock for the purpose of commercial profit, and are only marginally involved in the external economy. They lead a full-time subsistence-oriented pastoral way of life. Because the most distinct feature of the precipitation in Rendilleland is its wide variation in both time and space, the herders are forced to lead the livestock to places of pasturage and water as occasion may demand. Moreover, many herders are required to maintain m'.llti-typed pastoralism, where many types of livestock with different characteristics in physiology and ecology are raised in combination. To cope with these problems, the Rendille organize