Posttraumatic stress disorder (PTSD) frequently co-occurs with myriad mood and anxiety disorders including generalized anxiety disorder (GAD). Despite this comorbidity's prevalence, mechanisms underlying the co-occurrence of PTSD and GAD remains understudied. An emotion dysregulation framework routinely is used to understand both PTSD and GAD but has not been applied to the PTSD-GAD comorbidity. Using MANOVA, the present study tested domains of emotion dysregulation (DERS) and of positive emotion regulation (AEQ) as differentiators of PTSD alone versus PTSD with GAD using pre-intervention data from a randomized controlled trial including 292 women with PTSD secondary to interpersonal violence. Five of six emotion dysregulation domains differentiated the two groups: fewer regulation strategies, nonacceptance of emotional responses, impulse control difficulties, lack of emotional awareness, and lack of emotional clarity were associated with comorbidity. Of three positive emotion regulation domains, participants with PTSD alone reported more positive emotionality than those with PTSD and GAD, and those with comorbid PTSD and GAD reported more negative affective interference than those with PTSD only. Rather than specific domains underlying unique presentations, findings indicate a general dysregulation factor, where PTSD-GAD comorbidity is supported by an overall higher level of emotion dysregulation as compared to PTSD alone.