Effective strategies aimed at prison sexual assault require inmates to possess the same definition of sexual assault as prison administrations. This article argues that prison culture is rape-supportive and inmates may not define sexual assault as such. After analyzing questionnaire responses given by male and female inmates in a large Southern prison system, results suggest that increases in subscriptions to inmate rape-supportive beliefs restrict acts of sexual violence from being defined as sexual assaults. Policy recommendations focus on changing inmate culture in addition to informing inmates about what behaviors constitute prison organizations' definition of sexual assault. (Contains 2 tables and 2 notes.)