Humans demonstrate altruistic behaviors in a variety of contexts [1,2], but there is growing experimental evidence that our closest living primate relative, the chimpanzee, does not always share our human prosocial tendencies [3,4]. Although chimpanzees behave cooperatively in some contexts, there is growing evidence that chimpanzees are indifferent to others' needs when food is involved. Indeed, a number of studies have shown that chimpanzees fail to selectively donate food to others even when they do so at no cost to themselves [3,4]. Chimpanzees' lack of other-regarding preferences in these recent studies had initially caused many researchers to conclude that humans are alone in our capacity for prosocial giving. Researchers have therefore begun exploring why humans' prosociality differs from that of closely-related primates, leading some to observe that humans' prosocial tendencies might stem specifically from their history as reproductively cooperative breeders (see [5,6] for evidence of prosocial giving in cooperatively breeding primates). Here, we test this claim directly, providing a surprising demonstration that one non-cooperative breeder, the tufted capuchin monkey (Cebus apella), reliably exhibits prosocial behavior in a food-sharing task modeled after a human economic task known as the Dictator Game [2].