Peer support has shown modest yet consistent positive effects on recovery outcomes for serious mental illness (SMI). While substance use is relatively common in SMI populations, there is relatively little clinical research for peer support on alcohol and substance use disorder (SUD) outcomes in these populations. At a time when recovery support is increasingly sought through online forums (e.g., social media communities, chat rooms), special considerations are needed for the use of these resources in SUD recovery for people affected by SMI. While support via online forums can be beneficial for individuals who are seeking recovery from SUDs, for certain individuals with SMI, these dynamics may be detrimental (e.g., physical isolation and media addiction, misinformation contributing to reality distortions, perceived rejection aggravating personality disorder symptoms). This presentation provides considerations for the use of online forums for SUD recovery in SMI populations.