Cigarette smoking is a serious public health concern, and is especially prevalent among college students. Although many college smokers try to quit, few are successful. Both peer smoking status and social support have been correlated with smoking initiation and maintenance, but few studies have investigated relapse. Further, personality-level predictors of relapse have rarely been studied. It is important to examine mechanisms underlying relapse in order to usefully modify and individualize smoking cessation interventions. The present study tested the hypotheses that social support would impact college student relapse rates at one-week follow-up during a self-quit, and that this relationship would be moderated by the trait of sensitivity to ostracism. In a sample of 41 college smokers, only best friend smoking status and frequency of modeling behaviors (e.g. offering quitter a cigarette) were found to predict relapse. Additionally, sensitivity to ostracism predicted how helpful/hindering quitters perceived peer support/criticism to be.