I defend resentment as a legitimate and necessary moral attitude by neutralizing an objection that points to its hostile and morally repugnant character. The argument proceeds by embedding resentment in a view of morality as a social and communicative practice, supported by a common knowledge of apparently inborn moral expectations. In virtue of these natural expectations, every person is pre-institutionally entitled to goodwill and to the pleasure that arises from showing and receiving goodwill from others. Resentment arises naturally when these expectations are violated: it is a reaction to an offence, leading to a dynamic exchange that aims to restore a broken moral relationship between persons. The offender participates in this communicative exchange by undergoing a form of punishment that is self-imposed and expressed through feelings of guilt and contrition. Keywords: blame, compatibilism, goodwill, moral reparation, reactive attitudes, sympathy.