Lesbian, gay and bisexual (LGB) emerging adults experience higher rates of trauma and discrimination, and subsequent PTSD and depression, than heterosexual emerging adults (Feinstein et al., 2012; Hatzenbuehler et al., 2008; Roberts et al., 2010). Our understanding of the relations between trauma/discrimination and psychiatric sequelae in LGB emerging adults is limited by: (1) uncertainty in the possible differential impact of LGB-specific trauma versus non-LGB-specific trauma, (2) uncertainty of the unique impacts of trauma and discrimination, and (3) lack of studies integrating cognitive theories of trauma (Brewin & Holmes, 2003) into Hatzenbuehler’s (2009) psychological mediation framework. This cross-sectional study included 82 gay men, 102 lesbians, 21 bisexual men, and 139 bisexual women (total N = 344; ages 18-25), all of whom experienced discrimination, trauma, and/or heard of other LGBs’ traumatic and/or discriminatory experiences. To understand the relations of trauma and discrimination to psychiatric sequelae, we investigated the unique and combined impacts of LGB-specific discrimination, trauma, and vicarious trauma and non-LGB-specific trauma on PTSD and depression symptoms. To test the psychological mediation framework, we evaluated whether blame cognitions and rejection sensitivity mediated these relations. Findings indicated that LGB-specific discrimination and vicarious trauma, and non-LGB specific trauma are positively and uniquely associated with PTSD and depression symptoms. Blame cognitions mediated the relations between discrimination, vicarious trauma, and non-LGB specific trauma, and PTSD and depression symptoms, supporting the psychological mediation framework. This study’s clinical implications include broader assessment of traumatic and discriminatory experiences and LGB-affirmative modifications for trauma-informed interventions post-trauma and discrimination