Post Traumatic Stress Disorder (PTSD) is common in the general population with the National Comorbidity Survey reporting a lifetime prevalence of about 8% in the United States (Kessler, et al 1995). PTSD is associated with marked symptomatic distress as well as significant impairment, dysfunction and reduction in overall quality of life (Kessler, 2000). Both pharmacotherapeutic interventions, including serotonin selective reuptake inhibitors (SSRIs), and psychosocial interventions such as cognitive-behavior therapy (CBT) have demonstrated efficacy for PTSD (Davidson, 2001; Foa, 2000) However, although these interventions can be helpful, many patients remain symptomatic despite initial treatment. There is little data available to guide practice regarding the efficacy of "next step" strategies for patients remaining symptomatic despite treatment.