Posttraumatic stress disorder (PTSD) is prevalent in youth involved in delinquency, but it is often not effectively treated. A randomized clinical trial was conducted comparing the outcomes of an emotion regulation therapy (Trauma Affect Regulation: Guide for Education and Therapy, or TARGET) with a relational supportive therapy (Enhanced Treatment as Usual, or ETAU) with 59 delinquent girls (age 13-17 years) who met criteria for full or partial PTSD. Mixed model regression analyses demonstrated generally large effects for pre-post change in PTSD symptoms for both therapies but not in emotion regulation. Both therapies had small to medium effect size changes in anxiety, anger, depression, and posttraumatic cognitions. Treatment x Time interactions showed small to medium effects favoring TARGET for change in PTSD (intrusive reexperiencing and avoidance) and anxiety symptoms, posttraumatic cognitions, and emotion regulation, and favoring ETAU for change in hope and anger. Results provide preliminary support for TARGET as a potentially efficacious therapy for PTSD with delinquent girls. Relational therapies such as ETAU also may be beneficial for delinquent girls with PTSD, particularly to enhance optimism and self-efficacy and reduce anger. (Contains 1 figure and 1 table.)