Data were collected with a victimization survey. Every inmate in each of the institutions was approached in person and asked to complete a 12-page questionnaire that dealt primarily with his personal experience of victimization in the past month. Ninety-two percent of the inmates agreed to complete the questionnaire. The types of victimization addressed in the survey were assault, robbery, threats of violence, cell theft, verbal abuse, and exclusion. Self-reports show victimization to be frequent, particularly among young offenders, of whom 30 percent had been assaulted and 44 percent threatened with violence on at least one occasion in the previous month. For adult inmates the respective figures were 19 percent and 26 percent. Although many of these incidents were minor, the fact that one-third of young offenders and one-fifth of adult male prisoners had been assaulted in 1 month shows a level of harmful activity that is frustrating for staff, frightening for inmates, and potentially destabilizing for regimes. The routine victimization found in this study shapes the social ethos of prisons and young-offender institutions. The potential for assault, theft, and verbal abuse influences their attitudes about the boundaries of acceptable behavior. Previous experience of custody did not reduce the risk of being victimized. These findings show the need for the Prison Service to continue to build on the initiatives already in place for reducing the risks of victimization while in correctional custody. 1 table, 2 notes, and 35 references