In 2005, there were 20,888 prisoners in the U.S. prisons known to be HIV-positive, many substance-involved. The high reincarceration rate of substance-involved prisoners, coupled with the fact that substance-involved prisoners are more prone to HIV-risk behaviors in the community, necessitates attention to preventing substance use and HIV transmission risk behaviors of prisoners upon reentry to communities. We use a social support framework to explore the role of social support in HIV+ prisoners' expectations of release and postrelease plans. Interview data from 23 participants were collected from August 2005 to January 2006. Participants reported concerns about their ability to access needed formal and informal prosocial support upon release. Implications of these findings for release planning are discussed. (Contains 1 table.)