Objective: The primary aim of this study was to explore the potential moderating effect of social support on the relation between distress caused by psychosis risk symptoms and self-stigma among college students with mental health diagnoses. Methods: Participants were young adult college students who endorsed having a past or present mental health diagnosis (n = 63). Self-report data were examined from the Prodromal Questionnaire-Brief, a measure of subthreshold psychosis risk symptoms; the Self-Concurrence/Application subscale of the Self-Stigma of Mental Illness Scale, a measure of self-stigma; and the Friendships subscale of the Lubben Social Network Scale-Revised, a measure of social support from peers. Results: There was a modest direct relation between distress associated with psychosis risk symptoms and self-stigma. There was a larger relation between distress from risk symptoms and self-stigma for those with low social support compared to those with mean and high social support. Conclusions and Implications for Practice: Although causality cannot be determined based on this study, a strong relation between symptom distress and stigma was found among those reporting low peer social support. Interventions that target both self-stigma and social support might be relevant for young adults with a history of mental health concerns who currently endorse subthreshold psychotic symptoms.