["Journal of Traumatic Stress, EarlyView. ", "\nAbstract\nSexual minority individuals are at increased risk for developing mental health disorders, including obsessive–compulsive disorder (OCD) and posttraumatic stress disorder (PTSD). Prior research has identified that individuals with comorbid OCD and PTSD may have a more complex clinical presentation and worse treatment outcomes. Although PTSD is not the main focus of exposure with response prevention (ERP), the first‐line therapy for OCD, symptoms are inadvertently targeted through overlapping mechanisms with exposure‐based PTSD treatments. No prior research has compared sexual minority and heterosexual individuals receiving treatment for OCD regarding trauma history and posttraumatic stress symptom (PTSS) treatment outcomes. Participants (N = 696) included heterosexual (n = 554, 80.0%); bisexual, pansexual, and/or queer (bi+ ; n = 87, 13.0%); gay/lesbian (n = 39, 5.6%); and asexual (n = 16, 2.3%) adults in treatment for OCD and related disorders. Sexual minority participants were significantly more likely to report experiencing an interpersonal traumatic event compared to heterosexual participants, χ2(1, N = 695) = 5.97, p = .015. No significant differences were identified regarding noninterpersonal trauma, χ2(1, N = 695) = 0.84, p = .360. Further, bi+ participants reported significantly higher PTSS at baseline compared to heterosexual participants, but gay/lesbian and asexual participants did not differ from heterosexual participants. Participants reported significantly improved PTSS while receiving ERP, and this did not differ by sexual minority status. Clinical implications include assessing trauma among sexual minority patients, especially bi+ individuals; utilizing trauma‐informed care; and incorporating sexual minority stressors into treatment for OCD.\n"]