This study investigated: (1) the level of thinking of the Iteso Primary School children in Uganda; and (2) whether abilities involved in the Piagetian tasks of conservation, classification, and seriation develop at the same rate. The subjects, ages 6 to 13 (the period of the 7-year African primary school) were interviewed in their own language and were tested with materials native to their area. This approach yielded results that were more representative of the children's thinking than have been obtained in other cross-cultural studies. The results generally support the Piagetian theory of development. It is suggested that further research into all aspects of child thought should be conducted. (ST)