We investigated the kinds of biological properties that children aged 3-6 years attribute to animals, plants, and artifacts by administering a property attribution task and eliciting explanations for the resulting property attributions. Findings indicated that, from the age of 3 years, children more frequently attribute properties to animals than they do to plants or artifacts. Moreover, attributions increased with age for animals, decreased for artifacts, and remained constant for plants. Concerning the conceptual development of animals and plants, results showed that the properties subtending children's initial conceptualization of animals are movement and nutrition, followed by growth, backed up by perceptual, biological, and categorical explanations. By contrast, for plants, the properties are growth and then movement, backed up by perceptual and biological arguments. These findings provide some support for the idea that both conceptual information and perceptual cues influence children's conceptual development.