Narratives pervade almost any aspect of our life and play a particularly important role in moral and prosocial decision-making. We study how positive (stories in favor of a prosocial action) and negative (stories in favor of a selfish action) narratives influence prosocial behavior. Our main findings are that positive narratives increase giving substantially, especially for selfish types, compared to a baseline with no narratives. Negative narratives, on the other hand, have a differential effect. Prosocial types decrease their giving, while selfish types give more than in the baseline. We also find that positive narratives lead to a binary response (comply or not comply), while negative narratives induce a more gradual trade-off.