To examine cross-cultural differences in behavior upon witnessing peer victimization and the reasons behind the behavior, this study evaluated the responses of early adolescents from both the United States and Taiwan. Two questions were addressed: (1) Do adolescents in Taiwan and in the United States differ in their willingness to help peer victims, and/or in the endorsement of specific help and non-help behaviors when assessed with a vignette? And (2) do adolescents in Taiwan respond and reason about their responses in the same way as do U.S. early adolescents when they witness real-life victimization? Four-hundred seventy U.S. 6th graders attending three public middle schools within the Midwest United States and 731 Taiwanese 7th graders from one middle school in southern Taiwan completed a survey that contained both open-ended questions asking about real-life reports of witnessing peer victimization and a vignette assessing responses to a hypothetical victimization event. Similarities and differences were found in witness responses from adolescents in the two cultural groups. Taiwanese adolescents were more likely to offer comfort to the victim and U.S. adolescents more likely to tell the bully to stop. Cultural values of interdependence versus independence were reflected in the reasons behind witness responses. Suggestions regarding how anti-victimization intervention and prevention programs should be tailored when they are introduced across the two cultural contexts are discussed.