The purpose of the present study was to examine the role of posttraumatic stress symptoms (PTSS) in predicting substance use and substance-related problems in a sample of older youth and emerging adults involved with child welfare. The sample was drawn from the Maltreatment and Adolescent Pathways (MAP) longitudinal study (Wekerle et al. 2009). Participants were 253 youth and emerging adults (ages 15-20; M = 16.87, "SD" = 1.04; 61.4% female and 38.6% male) who were involved with child welfare. Multiple regression analyses were conducted to examine the impact of PTSS using subscales from the Trauma Symptom Checklist for Children (TSCC; Briere 1996). Outcome variables were past year alcohol, marijuana and illicit drug use; as well as alcohol and drug problems. Controlling for gender, age, child welfare status and child maltreatment, both dissociation and anger emerged as significant predictors of substance use and related problems. The implications of these findings for older youth and emerging adults exiting the child welfare system are discussed.