Black girls bear a higher burden of juvenile justice involvement in the United States, relative to other racial/ethnic female groups. Emerging evidence suggests that system involvement is related to trauma histories and post-traumatic stress disorder (PTSD). This study investigated the associations between individual, family, and peer factors, and their relationship to PTSD among Black girls with juvenile justice involvement. Cross-sectional data were collected from 188 Black girls in detention. Measures assessed were history of abuse, negative peer norms, future orientation, caregiver support, self-esteem, age, and PTSD symptoms. Major regression findings indicated that higher rates of caregiver support, higher negative peer norms, lower self-esteem rates, and lower future orientation rates were correlated with greater PTSD symptoms. Treatment programs for this population warrant a multisystemic approach, which includes caregivers and peers, and bolstering important constructs such as self-esteem and hopefulness.