Review DEPRESSION AND ANXIETY 27 : 1017–1026 (2010) POSTTRAUMATIC STRESS AND SOCIAL ANXIETY: THE INTERACTION OF TRAUMATIC EVENTS AND INTERPERSONAL FEARS Kelsey C. Collimore, M.A., 1 R. Nicholas Carleton, M.A., 1 Stefan G. Hofmann, Ph.D., 2 and Gordon J.G. Asmundson, Ph.D. 1Ã Posttraumatic stress disorder (PTSD) and social anxiety disorder (SAD) are frequently comorbid among veteran and community samples. Several studies have demonstrated significant comorbidity between trauma, PTSD, and social anxiety (SA), and a growing number of studies have explored the nature of this association. Although a diagnosis of either PTSD or SAD alone can result in significant impairment in social and occupational functioning, these difficulties are often magnified in persons suffering from both disorders. This review describes the current state-of-the-art regarding the co-occurrence of trauma, PTSD, and SA. First, we provide an overview of empirical data on the prevalence of co-occurring trauma, PTSD, and SAD. Second, we describe possible explanatory models of the co-occurrence, with a specific focus on the shared vulnerability model. Third, we review the available empirical data addressing the postulates of this model, including both genetic and psychological vulnerabilities. Fourth, we describe additional factors—guilt, shame, and depressive symptoms—that may help to explain the co-occurrence of PTSD and SA. A better understanding of this complex relationship will improve the efficacy of treatment for individuals suffering from both disorders. We conclude with key areas for future research. Depression and Anxiety 27:1017–1026, 2010. r r 2010 Wiley-Liss, Inc. Key words: anxiety disorders; social anxiety; social phobia; posttraumatic stress disorder; trauma INTRODUCTION The co-occurrence of posttraumatic stress disorder (PTSD) and social anxiety disorder (SAD) is common but understudied. Although several investigations have been conducted on the co-occurrence of traumatic events, PTSD, and SAD, there have been few systematic attempts to better understand the nature of this association. Understanding the relationship between PTSD and SAD is particularly important, because positive social activity has a substantial influence on quality of life following trauma, [1,2] and social support has been found to facilitate posttrauma recovery. [3] This article presents an integrative review of the empirical literature on trauma, PTSD, and SAD. We first review empirical data on the prevalence of co- occurring trauma, PTSD, and SAD. This is followed by discussion of possible explanatory models of co-occurrence, with a specific focus on the shared vulnerability model. Thereafter, we review available Published online 18 August 2010 in Wiley Online Library (wiley onlinelibrary.com). DOI 10.1002/da.20728 Received for publication 1 March 2010; Revised 12 June 2010; Accepted 16 June 2010 The authors disclose the following financial relationships within the past 3 years: Contract grant sponsor: Canadian Institutes of Health Research (CIHR) Investigator’s Award; Contract grant number: 63186; Contract grant sponsor: CIHR Doctoral Research Award; Contract grant number: 85321. Ã Correspondence to: Gordon J.G. Asmundson, Anxiety and Illness Behaviours Laboratory, Department of Psychology, University of Regina, Regina, SK, Canada. E-mail: gordon.asmundson@uregina.ca 1 The Anxiety and Illness Behaviours Laboratory, Department of Psychology, University of Regina, Regina, Saskatchewan, Canada 2 Department of Psychology, Boston University, Boston, Massachusetts r r 2010 Wiley-Liss, Inc.