Prolonged exposure (PE) is an efficacious and effective treatment for PTSD that has been studied extensively and disseminated around the world. The theoretical underpinning of PE is emotional processing theory (EPT; Foa and Kozak 1985, 1986), an influential theory of pathological anxiety and therapeutic recovery. In this chapter, we briefly review EPT’s account of the development and treatment of PTSD. We then describe the structure and key components of PE and illustrate its delivery using a case example. Next we provide an overview of the most common challenges faced by therapists delivering PE and discuss ways of overcoming these obstacles to maximize benefit from PE. We end our discussion with a summary of the extensive evidence supporting the efficacy and effectiveness of PE for a wide range of PTSD sufferers.