There is broad consensus that the strains of imprisonment and unsupported release affect offenders' mental health and operate to the detriment of their chances of successful reintegration. Drawing on data from 208 male inmates, the authors examine the mediating and moderating influences of social support on the links between inmates' perceptions of prison conditions and other background variables on parolees' feelings of hostility--a factor theoretically linked to reoffending--upon release. The results demonstrate that social support partially or completely mediates background characteristics and conditions the influence of prison perceptions on released inmates' levels of hostility. (Contains 3 tables and 1 figure.)