Indigenous ideas regarding cognitive development have been largely ignored as an area of study for social anthropologists in Britain. Nor was this an issue that I planned to investigate when I first went to do fieldwork among the Chewong of the Malay Peninsular. However, I was interested in studying the Chewong concept of self, that is, what it means to be a human being, and this is a topic which, I would argue, is central to any discussion of cognitive development; since the process of acquiring knowledge of all kinds can be delineated only by eliciting the socially agreed expectations of what it is that a child is to become. What I shall attempt to do in this chapter, therefore, is to discuss Chewong notions of what constitutes a child and an adult (i.e. a 'human'), and then examine the process whereby the one is changed into the other. This will involve reviewing all the stages in the developmental cycle. I shall be arguing that in the Chewong case, this cycle starts before birth and continues beyond physiological and social maturation. Thus it is necessary to modify, or even abandon, Western models of cognitive development to take account of a society such as the Chewong, in which the range of the process is extended and the stages differently perceived.