We investigated the relationship between emotions of fear and anger and people’s motivation for intergroup aggression within the context of Serbian—Albanian relations in Serbia (Study 1) and Serbian—Bosniak intergroup relations in Bosnia (Study 2). Serbian students in Belgrade and Banja Luka completed a survey that assessed their attitudes towards Albanians or Bosniaks. We found that fear of the outgroup was related to increased motivation for aggression in the context of the ongoing conflict in Serbia, whereas fear was negatively related to aggression in Bosnia, where the conflict had been resolved. The relationships between fear and aggression were significant even after controlling for anger. Furthermore, ingroup affiliation mediated the relationship between fear and aggression in Serbia and between anger and aggression in Bosnia. These findings have implications for conflict resolution efforts in ongoing or intractable conflicts.