||Young children's vocabulary size is a strong predictor of future academic success, especially reading abilities (Senechal & LeFevre, 2003; Stanovich, 1986). However, measures of vocabulary size assess word knowledge at a surface level, that is, they assess recognition of word/referent associations. The purpose of this study was to gain further understanding of preschool children's elaborated word knowledge. Acquiring elaborated word knowledge appears to be a long-term process of integrating many kinds of information about a word's referents, such as functional information, and making new connections between words. Preschool (3- and 5-year-olds) children were given a word definition task and an indirect assessment of taxonomic knowledge. The results of both tasks suggest that age and vocabulary size are related to elaborated word knowledge. Socioeconomic status, which previous research has found to predict elaborated word knowledge, was a significant predictor only of children's taxonomic knowledge, suggesting that SES has a unique effect on taxonomic knowledge.