Mediumistic divination is unique to the Nguni, as all other Bantu-speakers in southern Africa used a fairly ‘objective’ divinatory system involving a set of four incised bone tablets, or an assortment of astragals, shells and other objects (or a combination of both). Also, unlike non-Nguni, Nguni diviners were predominantly women. They were called to the profession through a life-transforming, ancestor-sent illness (thwasa) characterised by psychological and physical symptoms. The article discusses the nature, and possible correlates, of these differences. It is argued that the form of Nguni divination is connected with three related aspects of Nguni social arrangements that distinguish them from other southern African Bantu-speakers, namely the presence of strong patricians, the conceptualisation of the ancestors as a transcendent, undifferentiated collectivity, and the marked subordination of women. In addition, there is evidence of both the borrowing of certain aspects of the San trance dance, as an appropriate expression of female tensions, and, especially among Cape Nguni, of the concept of divinatory animals. This San influence is much less evident among the Zulu. The importance of appreciating the essentially selective nature of cultural borrowing is emphasised.