Purpose: Lesbian, gay, bisexual, and transgender (LGBT) youth show increased risk for a number of negative mental health outcomes, which research has linked to minority stressors such as victimization. Further, social support promotes positive mental health outcomes for LGBT youth, and different sources of social support show differential relationships with mental health outcomes. However, little is known about how combinations of different sources of support impact mental health. Methods: In the present study, we identify clusters of family, peer, and significant other social support and then examine demographic and mental health differences by cluster in an analytic sample of 232 LGBT youth between the ages of 16 and 20 years. Results: Using k-means cluster analysis, three social support cluster types were identified: high support (44.0% of participants), low support (21.6%), and non-family support (34.5%). A series of chi-square tests were used to examine demographic differences between these clusters, which were found for socio-economic status (SES). Regression analyses indicated that, while controlling for victimization, individuals within the three clusters showed different relationships with multiple mental health outcomes: loneliness, hopelessness, depression, anxiety, somatization, general symptom severity, and symptoms of major depressive disorder (MDD). Conclusion: Findings suggest the combinations of sources of support LGBT youth receive are related to their mental health. Higher SES youth are more likely to receive support from family, peers, and significant others. For most mental health outcomes, family support appears to be an especially relevant and important source of support to target for LGBT youth.