Previous research has documented that playing violent video games has various negative effects on social behavior in that it causes an increase in aggressive behavior and a decrease in prosocial behavior. In contrast, there has been much less evidence on the effects of prosocial video games. In the present research, 4 experiments examined the hypothesis that playing a prosocial (relative to a neutral) video game increases helping behavior. In fact, participants who had played a prosocial video game were more likely to help after a mishap, were more willing (and devoted more time) to assist in further experiments, and intervened more often in a harassment situation. Results further showed that exposure to prosocial video games activated the accessibility of prosocial thoughts, which in turn promoted prosocial behavior. Thus, depending on the content of the video game, playing video games not only has negative effects on social behavior but has positive effects as well.