This planning grant will support preliminary studies concerning infants' beliefs about what kinds of things in the world have mental states such as intentions and perceptions. Previous research has focused largely on determining when infants first conceive of people as entities with minds, on the assumption that infants attribute mentality only to humans. This project proceeds from the view that infants may attribute mental states to a broader range of entities. From this perspective, a central question is, On what grounds do infants make mental state attributions? My previous research has shown that 12-month-old infants will follow the `gaze` of an animated object that bears no physical resemblance to a person, as long as it has other properties characteristic of creatures with minds, such as goal-directed behavior or facial features. Gaze-following refers to the familiar behavior in which one person, the `follower,` turns to see what another person is looking at, and is thought to reflect the follower's belief that the gazer has mental states such as attention, perception, and goal-directedness. The proposed research explores the nature and development of the knowledge that underlies gaze-following behavior in infancy. This goal will be pursued by exploring 1) the characteristics that elicit gaze-following in infancy, 2) developmental changes in these characteristics between the ages of 9 and 18 months, and 3) the relationship between object characteristics that elicit gaze-following behaviors and those that elicit attributions of intentionality as revealed by other behaviors such as the imitation of perceived goals. The findings of this work will further our understanding of how infants come to reason about a social and mental world that includes not only people but also other kinds of objects.