We describe an experimental investigation of the development of children's knowledge stmctures which aims to provide data for connectionist modelling. 167 children between 5 and 11 years of age completed two category fluency tasks where they were asked to produce as many names of a) animals and b) parts of the body, as they could in one minute. Similarity scores were derived based on distances between concepts in the lists produced. These were analysed using the ADDtree algorithm (Sattath & Tversky, 1977) to build structures representing the organisation of the children's knowledge of animals and body parts. The results showed that animal knowledge was generally organised in terms of environmental context/habitat, however, there was evidence for subtle changes in knowledge organisation between age groups. More pronounced changes were observed in the organisation of knowledge of body parts which gave some support to the assertion that children progress from making coarser to making fmer distinctions between concepts (see Keil, 1979) and reflected the progression observed in knowledge structure development in a connectionist model of semantic memory discussed by McClelland, McNaughton and O'Reilly (1995). Our aim is to extend this work to provide data enabling connectionist modelling of semantic memory within a developmental framework.