Institutions of higher education increasingly offer training programmes to engage students’ as pro-social bystanders who can intervene in situations related to sexual violence. The purpose of this study was to assess the usage of a bystander behaviour measurement tool that captures both students’ intervention opportunities and frequency of prosocial response. University undergraduate students in the Northwestern USA (n=474) completed online surveys in the Fall of 2016. Results show that students have opportunities to intervene in a variety of situations at the three levels of prevention for campus sexual violence and they do not always intervene. The frequency of students’ prosocial bystander response ranged, for those with the opportunity, from ‘never’ to ‘always’; students reported varying degrees of intervention frequency depending on the situation. A bystander intervention behaviour instrument measuring opportunity and frequency of response can be a valuable tool for assessing the effectiveness of bystander training programmes.