While the relationship between sexual trauma and risky sexual behavior (RSB) has received much attention, only a handful of studies have investigated the factors that protect victims of sexual trauma from developing this maladaptive pattern of behavior. The current study investigated the protective role of social support, quality and quantity, in developing RSB, through the mechanism of problematic substance use. Two hundred and seventy-five female college students completed a series of self-reports assessing sexual trauma, problematic substance use, social support quality and quantity, and RSB. The results indicated a positive relationship between sexual trauma severity and RSB. Further, this relationship was mediated by participants' problematic substance use. Social support quality acted as a buffer against the relationship described above where quantity exacerbated this relationship. Implications will be discussed.