We investigate parochial altruism, the combination of in-group altruism and out-group hostility, in an experimental conflict game preceded by a prisoner’s dilemma. Our data are consistent with parochial altruism, but cannot be explained by in-group pro-sociality or out-group hostility alone.

We introduce the joy-of-destruction game. Two players each receive an endowment and simultaneously decide on how much of the other player's endowment to destroy. In a treatment without fear of retaliation, money is destroyed in almost 40% of all decisions.