Victims of substance-involved sexual assault often experience worse post-assault outcomes than other sexual assault victims. These outcomes may be exacerbated by their heightened risk of receiving negative reactions when disclosing their assault to informal disclosure recipients, such as friends, family members, and intimate partners. To date, little research has explored the associations between informal disclosure recipient and receipt of positive and negative reactions among victims of substance-involved sexual assault. Our sample included data about 400 victims of substance-involved sexual assault (91% women; 30% minors) who visited an anonymous sexual assault hotline and discussed reactions received during their first disclosure to an informal support provider. Using logistic regressions, we examined how the type of informal recipient to whom the victim disclosed was associated with receipt of positive and negative reactions, controlling for individual and situational characteristics (e.g., victim gender, perpetrator). Negative reactions were more common than positive reactions (65% vs. 47% of victims, respectively). Victims who disclosed to family members had lower odds of receiving positive reactions and higher odds of receiving negative reactions than those who disclosed to friends and intimate partners. Results support previous research that victims of substance-involved sexual assault commonly receive negative disclosure reactions, especially when disclosing to family members. Future work is needed to identify best strategies for improving support providers' responses to sexual assault disclosure, such as recent interventions focused on educating potential recipients about how to respond to disclosures. Further, our results highlight the utility of sexual assault hotlines as a data source for understanding the disclosure experiences of stigmatized victims underrepresented in traditional research.