Adverse childhood experiences (ACE) are associated with increased risk for psychopathology over the life course. However, few studies have examined the differential impact of ACE and posttraumatic stress disorder (PTSD) for racially and ethnically diverse adolescent populations. The findings from the few studies that examine differential effects are contradictory. This study uses data from the National Comorbidity Survey-Adolescent Supplement (NCS-A), a nationally representative adolescent sample (N = 10,123) to examine the impact of race/ethnicity on the association between ACE and PTSD among youth in a nationally representative sample in the United States. A multivariate logistic regression model was used to examine the main effects of ACE and race/ethnicity on PTSD, as well as the moderating role of race/ethnicity adjusting for socio-demographic variables. Findings suggest that race/ethnicity moderates the association between ACE and PTSD. Higher ACE score increased probability of lifetime PTSD for White non-Hispanic, Black, and Hispanic adolescents with White non-Hispanic adolescents presenting with a much higher probability of lifetime PTSD compared to their Hispanic and Black peers. Implications for future research and practice are discussed, specifically trauma informed strategies and culturally inclusive/specific practices that address the structural, interpersonal, and intrapersonal influences adolescent outcomes.