Traumatic experiences have been posited as one potential catalyst for the abrupt onset of obsessive-compulsive symptoms including compulsive hoarding. To determine whether traumatic life events (TLEs) might influence the expression of compulsive hoarding in obsessive-compulsive disorder (OCD), interview responses to the Posttraumatic Stress Disorder module of the Structured Clinical Interview for DSM-IV (SCID) were examined in 180 individuals with OCD. Compared to individuals with OCD who did not meet criteria for hoarding, participants classified as hoarders (24% of the sample) were significantly more likely to have reported at least one TLE in their lifetime. Patients who met criteria for hoarding and who had also experienced TLEs had significantly greater hoarding symptom severity than those hoarders not exposed to trauma. This association was found to be robust. That is, the relationship between TLEs and hoarding symptom severity was not better accounted for by age, age of OCD onset, depressive symptoms, general OCD symptomatology, or mood and anxiety comorbidity. Closer examination revealed that the clutter factor of compulsive hoarding (and not difficulty discarding or acquisitioning) was most strongly associated with having experienced a traumatic event.