This study found that: male and female inmates reported that prison rape did not occur often; inmates “self-police” their own community in an effort to maintain peace and social order; inmates reported culturally prescribed social arrangements that facilitate physical safety and provide social and emotional support; inmate sexual culture allows for disagreement on inmates’ judgment of an act of sexual violence as coercive or rape; prison inmates judge prison rape as detrimental to inmates’ social order; and while men’s and women’s prisons display distinctions in social arrangements and overt social behavior, they share underlying cultural beliefs, values, and norms on the nature of sexuality and sexual violence. Results showed that inmates’ lack of confidence in institution protection may be linked to many conditions affecting low confidence in institution safety; inmate debts lead to violence; inmates have a low confidence in institution transfers as a means to prevent or intervene on situations of sexual pressure; and that protective custody falls short of creating inmate confidence in institutional safety. Qualitative and quantitative analysis of data both confirmed previous knowledge of inmates shared common cultural rules and brings new understanding of social-sexual behavior. Whether inmates determine that a sex act was consensual or forced rests on subjective perceptions of the causes of the act and the response of the victim toward the assailant. Inmates judge prison rapists as dangerous and victims as too weak to protect themselves. Practical innovations to prison rape prevention, such as security cameras, may provide greater inmate safety and inmates would benefit from an officially sponsored orientation to the realities of prison inmate culture. The study included 564 inmate volunteers (408 men and 156 women) from 30 prisons in 10 States.