The purpose of the study was to examine the association of personality disorders, history of trauma, and posttraumatic stress disorder (PTSD) in a large sample of subjects with anxiety disorders. Categorical and continuous indices of personality disorders were compared in three groups from the Harvard/Brown Anxiety Disorders Research Project (HARP): subjects with no history of trauma (n = 403), subjects with a history of trauma but no history of PTSD (n = 151), and subjects with a current or past diagnosis of PTSD (n = 68). Subjects with PTSD were more likely to meet criteria for borderline or self-defeating personality disorder than subjects in the other two groups. PTSD subjects also had higher scores on the continuous measures (total number of criteria met) for borderline and self-defeating personality disorder than the other two groups. The findings suggest that a diagnosis of PTSD rather than a history of trauma is associated with borderline and self-defeating personality disorder features. Alternative conceptualizations of axis II features in individuals with PTSD are discussed.