This study used recent advances in attitude and self-perception research to develop an Attitude to Non-Violence Scale (ANVS). Participants were students from six high schools in Australia (N = 727). Confirmatory factor analysis using within-construct and between-construct validation approaches found two positive attitude sub-scales: Cognitive (proactive understanding) and Affective (do not endorse violence), both showing convergent and discriminant validity. Scale equivalence tests found that the sub-scales were applicable to boys and girls and to junior and senior grades. Structural equation modeling found that boys had less supportive attitudes to non-violence cognitively, whereas female students in senior secondary classes had less positive attitudes to non-violence affectively. The ANVS can be easily administered to assess youth’s non-violence attitudes, which may direct interventions focusing on boys’ cognitive aspects while maintaining girls’ positive affective attitudes toward non-violence as they mature. The positively framed instrument is suitable for education settings especially in high-risk locations where violence is prevalent.