While both sets of variables were shown to exert independent effects on inmate aggression, variations in the institutional context mediated the impact of inmate characteristics on levels of prison violence. Preinstitutional violence emerged as the best predictor of inmate aggression, regardless of institutional setting. Race was shown to affect inmate violence directly only in the most treatment-oriented facility, while the inmate code was found to exert effects only in the most custodial institution. (Publisher abstract)