Two experiments tested an intervention approach to reduce young children's hostile attribution bias and aggression: self-persuasion. Children with high levels of hostile attribution bias recorded a video-message advocating to peers why story characters who caused a negative outcome may have had nonhostile intentions (self-persuasion condition), or they simply described the stories (control condition). Before and after the manipulation, hostile attribution bias was assessed using vignettes of ambiguous provocations. Study 1 (n = 83, age 4-8) showed that self-persuasion reduced children's hostile attribution bias. Study 2 (n = 121, age 6-9) replicated this finding, and further showed that self-persuasion was equally effective at reducing hostile attribution bias as was persuasion by others (i.e., listening to an experimenter advocating for nonhostile intentions). Effects on aggressive behavior, however, were small and only significant for one out of four effects tested. This research provides the first evidence that self-persuasion may be an effective approach to reduce hostile attribution bias in young children.