Trauma and dissociation may be important factors contributing to the experiences of distressing voice hearing. However, there is scant mention of how to target and treat such processes when working with people with psychosis. This case study reports on an initial attempt to work with dissociation and trauma memories in a person with voices. A single case approach was used, with standardized measures used before, during and after 24 sessions of cognitive therapy, and at 6-month follow-up. In addition, session-by-session measures tracked frequency and distress associated with voices and dissociation. The participant reported significant improvements in terms of reduced frequency and distress of dissociation, and voice hearing, as well as improvement in low mood at the end of treatment. At follow-up there were enduring benefits in terms of dissociation and trauma-related experiences, as well as broad recovery but not of change in voices. This case illustrated the potential benefit of targeting dissociation and exposure to trauma memories in producing general symptom improvement and specific reductions in dissociation and voice hearing at end of treatment.