This research was conducted to assess how guilt appeals operate in soliciting charitable donations. It was hypothesized that a sense of responsibility would enhance the effectiveness of charitable guilt appeals, thus leading to larger charitable donations. It was also hypothesized that the presence of others would make salient a prosocial norm, thus increasing a sense of responsibility to help. Two laboratory experiments were conducted to test these hypotheses. The effect of guilt on charitable-donation intention and actual donations was mediated by a sense of responsibility. Additionally, the presence of others enhanced the sense of responsibility to behave prosocially. These findings have implications for the design of charitable-donation campaigns. © 2006 Wiley Periodicals, Inc.