Selective serotonin reuptake inhibitor (SSRI) medication is often recommended in combination with cognitive behavioral therapies for PTSD, but combined initial treatment of PTSD has not been studied under controlled conditions. Also, there are few studies of either treatment in survivors of terrorism. This randomized controlled trial evaluates efficacy of combined prolonged exposure (PE) and the SSRI paroxetine in the treatment of survivors of the World Trade Center (WTC) attacks.