Recent Indigenist scholarship has situated high rates of traumatic life experiences, including sexual abuse, among Indigenous peoples of North America within the larger context of their status as colonized peoples. Sexual abuse has been linked to many negative health outcomes including mental, sexual and drug-related vulnerabilities. There is a paucity of research in Canada addressing the relationship between antecedent sexual abuse and negative health outcomes among Aboriginal people including elevated risk of HIV infection. The primary objectives of this study were to determine factors associated with sexual abuse among participants of the Cedar Project, a cohort of young Aboriginal people between the ages of 14 and 30 years who use injection and non-injection drugs in two urban centres in British Columbia, Canada; and to locate findings through a lens of historical and intergenerational trauma. We utilized post-colonial perspectives in research design, problem formulation and the interpretation of results. Multivariate modeling was used to determine the extent to which a history of sexual abuse was predictive of negative health outcomes and vulnerability to HIV infection. Of the 543 eligible participants, 48% reported ever having experienced sexual abuse; 69% of sexually abused participants were female. The median age of first sexual abuse was 6 years for both female and male participants. After adjusting for sociodemographic variables and factors of historical trauma, sexually abused participants were more likely to have ever been on the streets for more than three nights, to have ever self-harmed, to have suicide ideation, to have attempted suicide, to have a diagnosis of mental illness, to have been in the emergency department within the previous 6 months, to have had over 20 lifetime sexual partners, to have ever been paid for sex and to have ever overdosed. The prevalence and consequences of sexual abuse among Cedar Project participants are of grave concern. Sexual trauma will continue to impact individuals, families and communities until unresolved historical trauma is meaningfully addressed in client-driven, culturally safe programming.