In the present study, the authors investigated age differences in children's understanding (a) that a person's behavior may contribute to the formation of a shared opinion within the peer group and (b) that origins of a reputation can be direct or indirect. The authors read stories in which a target character engaged in either prosocial or antisocial interactions with peers to children in kindergarten, 2nd, and 4th grade. They then asked the children to judge how various peers viewed the target character. Children's explanations indicated that children in all of those age groups understood that firsthand experience influenced peers' opinions, and by 2nd grade, children understood that indirect experience or gossip also might have contributed to an individual's reputation. (Contains 3 tables.)