Previous research indicates that people with social anxiety disorder tend to experience escalating distress when thinking about past social situations. We investigated whether such distress could be limited by either an intervention or the participant's pre-existing abilities. Participants were 38 undergraduate students who reported problematic levels of social anxiety. Participants who endorsed a poor ability to purposefully engage with thoughts about stressful social situations reported a deterioration of mood after 25 min of unstructured writing about a recent problematic social situation, whereas those who demonstrated low levels of purposeful engagement but received writing prompts (based on cognitive restructuring techniques) did not show a strong deterioration of mood. In contrast, participants who endorsed greater purposeful engagement ability did not show such deterioration. Results suggest that the negative effects of thinking about social situations might be ameliorated, for at least some participants, if they are provided with structure.