The maltreatment of children is a public health and social concern, especially given the potential for negative consequences throughout the lifespan. Of particular interest for the current study is the well-established relationship between child maltreatment and alcohol use, drug use, and post-traumatic stress symptoms (PTSS) among adolescents. The current study examines how PTSS contributes to substance use and substance-related problems in a sample of older adolescents and emerging adults involved with the child welfare system. The current research is the secondary analysis of the Maltreatment and Adolescent Pathways (MAP) longitudinal study. Findings suggest that anger and dissociation, as two facets of PTSS, over and above background and maltreatment variables among older adolescents involved with the child welfare system were significant predictors of substance abuse and related problems. Authors suggest the findings are especially important for adolescents exiting the child welfare system and the need for increased supports during this time.