Many adolescents with substance-use disorder (SUD) have a history of trauma and symptoms of post-traumatic stress disorder (PTSD). Integrated cognitive behavior therapy (CBT) for co-occurring PTSD and SUD in adolescents is a phased intervention approach in which the same clinician or team of clinicians provides treatment for both disorders at the same time. This chapter discusses psychosocial conceptual models of the etiology of PTSD and the role of substance abuse, theory of change, target population, and CBT intervention parameters for integrated PTSD and SUD treatment programs.