Human beings are intensely social creatures and, as such, devote significant time and energy to creating and maintaining affiliative bonds with group members. Nevertheless, social relations sometimes collapse and individuals experience exclusion from the group. Fortunately for adults, they are able to use behavioral strategies such as mimicry to reduce their social exclusion. Here we test whether children, too, increase their imitation following an experience of ostracism. Given humans' profound need to belong, we predicted that the mere hint of social exclusion--even third-party social exclusion--would be sufficient to increase affiliative imitation in 5-year-olds. As predicted, children primed with videos in which one shape was ostracized by a group of other shapes subsequently imitated the actions of a model more closely than children in a control condition. These findings highlight just how sensitive humans are to social exclusion and demonstrate that children, like adults, modify their social behavior in response to ostracism.