The activities and social function of the Nguni diviner (Zulu, Baca isangoma; Xhosa igqira) has been described by a number of writers, notably Hunter and Kohler. This article gives an account of an initiation ceremony observed among the Baca of the Mount Frere district, East Griqualand and, as such, fills a gap in the published data on the subject.A person is “called” to the profession by the ancestral spirits and a diviner is conceived to be in a special relationship towards them. The initiation takes place after a year's preliminary training with an established doctor, during which time the novice attends séances (iintlombe) and acquires an extensíve knowledge of medicinal plants. Food and social taboos are observed and dreams play an important part in directing personal life. The initiation consists of séances, through which rapport is established with the spirits, and the ritual killing of a white goat (umthul’ entaeni) and a beast .(inkomo yokuphuma), the latter revealed to the novice in a dream. A final intlombe, held in the open air (this is the only occaion on which this occurs), when the novice dons the full regalia, marks the attainment of full professional status. Throughout she is supported by other diviners who attend the ceremony.A description of a typical thwasa dream is appended.