Emotions arise not just from people’s own circumstances, but also from the experiences of friends and rivals. Here we asked if human infants have expectations about vicarious emotions, and if they expect those emotions to be guided by social relationships. Ten- and 11-month-old infants (N=154) expected an observer to be happy rather than sad when the observer watched a friend successfully jump over a wall. In contrast, infants did not expect the observer to be happy when the friend failed, nor when a different, rival jumper succeeded. Infants are thus able to integrate information about desires and outcomes with knowledge of social relationships to infer others’ vicarious emotional responses. Biased concern for friends but not adversaries is not just a descriptive feature of human relationships, but an expectation about the social world present from early in development.