This study used graph analysis to investigate how age differences modify the structure of semantic word association networks of children and adults and if the networks present a small-world structure and a scale-free distribution which are typical of natural languages. Three age groups of Brazilian Portuguese speakers (children, adults and elderly people) participated in the experiment. Quantitative and qualitative measures suggested that adults and elderly speakers have similar network structures. Children's network showed fewer nodes, connections and clusters, and longer inter-node distances. All networks presented a small-world structure, but they did not show entirely scale-free distributions. These results suggest that from childhood to adulthood, there is an increase not only in the number of words semantically linked to a target but also an increase in the connectivity of the network. Keywords: Graph theory, word association, developmental age groups, semantic memory. ResumoEste estudo utilizou análise de grafos para investigar como a idade modifi ca a estrutura das redes de associações semânticas de palavras de crianças e adultos e se estas redes apresentam estrutura small-world e distribuição scale-free típicas de linguagens naturais. Participaram dos experimentos três grupos etários (crianças, adultos e idosos) falantes do Português Brasileiro. Medidas quantitativas e qualitativas sugeriram que adultos e idosos possuem redes semelhantes quanto a número de nós, conexões e agrupamentos. A rede das crianças expressou menor número de nós, conexões e agrupamentos e maiores distancias inter-nós. As redes apresentaram uma estrutura small-world, mas não uma distribuição scale-free completa. Os resultados sugerem que além do número de palavras semanticamente associadas aos alvos aumentar das crianças para os adultos, as redes se tornaram mais conectadas. Palavras-chave: Teoria dos grafos, associação de palavras, grupos etários, memória semântica.The structure and organization of human knowledge in terms of semantic relations have been the topic of much debate in areas such as cognitive sciences, psychology, and computer sciences. Nevertheless, the effects of age in semantic processing are not yet fully understood, mainly due to diverging research results. For example, Rönnlund, Nyberg, Bäckman, and Nilsson (2005), found a decline in semantic fl uency and vocabulary tasks, in participants from 60 to 85 years old. By contrast Park et al. (2002) showed an increase in the performance scores of vocabulary tests  Mailing address: