Children of ages 2 1/2, 3, and 3 1/2 years were tested for their understanding of object hiding, believed to reflect an early developmental level of knowledge about visual perception. Even the youngest subjects could nonegocentrically hide an object by placing it on the opposite side of a screen from another person, even though placing it there necessarily left it unhidden from themselves. In contrast, there was a significant increase with age in the ability to achieve the same physical end state by placing the screen between the other person and the object. Most subjects at each age level correctly indicated that the other person could see the object when the experimenter interposed the screen between the child and the object but that the other person could not see the object when she placed the screen between the other person and the object. These and other recent findings indicate that children of this age can be both nonegocentric and skillful at estimating what other people do and do not see under various viewing conditions.