Are chimpanzees able to inhibit anti-social behavior towards their friends? And how do they react when a friend acts anti-socially towards them? Past work has demonstrated that chimpanzees are selectively prosocial towards their friends: they groom them more, help them more, and share more food with them. However, the influence of friendship on anti-social behavior remains underexplored. Here, we use food theft as a test case to examine (1) the influence of friendship on anti-social behavior and (2) emotional responses to anti-social behavior. We assigned 26 chimpanzees to pairs of friends (friend condition) and non-friends (non-friend condition) based on 800 h of observations of naturally occurring interactions. The pairs then participated in a stealing task, in which one chimpanzee (the “thief”) could pull a tray with pieces of pineapple, on which the other was feeding (the “victim”). Friends and non-friends were matched on sex and dominance rank. We found that chimpanzees...