Summary.1.—Past investigations of the cognitive processes of primitive peoples are reviewed, with special reference to the continuum of abstract and concrete. It is pointed out that these studies have used Western type tests in reaching their conclusions. The present study differs in using indigenous material; the author, having lived among the subjects in the manner of an anthropologist, and speaking (inexpertly but sufficiently) the native language.2.—Bush and primary school children, living in the same area, were compared in their ability to classify and to sort (a) models of animals known in the area, (b) plants actually picked in the neighbourhood. The ability to shift from one classification to another and the basis of classification were investigated. The linguistic background relevant to the classifications is described.3.—Using familiar material there was found no difference between the two sets of children, of an age range from approximately 6 1/2 to 11 years. The results are discussed in the light of the general ability to abstract, in the sense of shifting from one class to another, and in the framework of the transition of the process of abstraction during this age period which comes under Piaget's period of “Concrete Oper