Youth violence is an important public health problem, but few researchers have studied violence from youth's perspectives. Middle school students' essays about the causes of youth violence were analyzed using qualitative and quantitative methods. The causes of violence identified by students were categorized into individual, peer, family, and societal factors. Seven to 11 subcategories were identified within each factor. Variations in the frequency of quotes among factors, the independent effects of factor and sex, and their interaction were examined. Peer factors were identified most often and family factors least often as causes of violence. Females were more likely than males to report peer factors as a cause. The most frequently mentioned subcategories within each factor were lack of anger management, need for acceptance, harassment/lack of respect, violence in the media, and parenting practices. The discussion examines youth's theories about the causation of violence and their implications for interventions.