Excessive rumination following traumatic or highly distressing experiences has been proposed to be an important maintaining factor of posttraumatic stress symptoms. However, not all forms of repetitive thinking about a negative event appear to be dysfunctional. It has been suggested that the abstractness of thinking is critical for its symptom-maintaining effects. The present study tested this hypothesis using an experimental analogue design with participants who had experienced a recent negative life event.After a short symptom provocation task, participants (N=57) wrote about their negative experience in either an abstract-evaluative or a concrete-experiential way. Intrusive memories were assessed during the session and in the first 36 h after the session.In line with the expectations, participants in the abstract-evaluative condition showed less reduction of intrusive memories during the experimental session than those in the concrete-experiential condition, and showed a slower recovery in the 36 h following the session.An analogue design was used. Therefore, results need to be replicated with survivors of traumatic events following DSM-IV.Taken together, the results support the idea that abstractness of thinking is responsible for the dysfunctional effects of rumination about a highly distressing or traumatic event.