Non-White sexual minorities experience disproportionate adverse childhood experiences (ACEs) and adulthood discrimination, as compared to their White or heterosexual counterparts. These stressors lead to increased psychological distress and worsened clinical outcomes, including suicidality. Minority stress theory posits that systemic marginalization, as experienced by minoritized individuals, leads to distress. Intersectionality theory suggests that marginalization compounds over time for individuals with intersectional minority identities. Yet, the mechanisms underlying the stress proliferation process for individuals with intersectional minority identities remain largely unexamined. The present study used nationally representative data of sexual minority individuals (n = 1,518, Mage = 31 years, ethnoracial minority = 38.7%, female and gender minority = 50.6%) to investigate the relations among ethnoracial minoritization, ACEs, discrimination, distress, and self-injurious/suicidal outcomes. We proposed a novel integration of minority stress, intersectionality, and stress proliferation theories. Via longitudinal mediation, we tested models of stress persistence, stress accumulation, and stress sensitization. Our results confirmed disparities between White versus non-White sexual minorities on ACEs, discrimination experiences, and psychological distress. We found support for the stress persistence and the stress accumulation models, but not the stress sensitization model. Moreover, we found distress and discrimination were associated with future nonsuicidal self-injurious behaviors and suicidal outcomes, highlighting the deleterious consequences of intersectional minority stress proliferation. Our results support our proposed theory of intersectional minority stress proliferation where ethnoracial and sexual minoritization intersect and beget disproportionate ACEs, which in turn contribute to accumulation and persistence of psychological distress and discrimination experiences in adulthood. (PsycInfo Database Record (c) 2024 APA, all rights reserved).