A growing body of research has highlighted connections between obsessive-compulsive disorder (OCD) symptoms and traumatic and stressful life events. However, findings regarding the impact of traumatic and stressful events on posttraumatic stress symptoms are mixed, with some studies suggesting that the perception of an event as traumatic—regardless of the strict definition of trauma—may be most predictive of outcomes. Despite this, research has yet to ask individuals with OCD, themselves, why they believe their OCD developed; instead, findings linking trauma exposure and OCD are largely causally extrapolated. The current study examined the perceptions of OCD etiology in 45 individuals with OCD enrolled in residential treatment and qualitative responses were coded as traumatic, stressful, or other (i.e., non-event) etiologies. Nearly half of the sample (44.4%) believed their OCD developed following an identifiable event, six of whom identified a distinguishable traumatic event (13.3% overall). Individuals with perceived traumatic etiologies consistently endorsed engagement in more obsessions and compulsions, particularly in the past, and implicated themes of symmetry/exactness, repeating, checking, scrupulosity, pathological doubt, and hoarding. Findings suggest that events that occur pre-OCD onset may be likely to be perceived as the catalyst for OCD and may ultimately impact the theme and severity of symptoms in intuitive ways.