Behavioural and Cognitive Psychotherapy, 2010, 38, 319–336 First published online 31 March 2010 doi:10.1017/S1352465810000111 A Randomized Clinical Trial to Examine Enhancing Cognitive-Behavioral Group Therapy for Obsessive-Compulsive Disorder with Motivational Interviewing and Thought Mapping Elisabeth Meyer, Fernanda Souza, Elizeth Heldt, Paulo Knapp and Aristides Cordioli Federal University of Rio Grande do Sul, Brazil Roseli G. Shavitt University of S ˜ ao Paulo, Brazil Carl Leukefeld University of Kentucky, USA Background: Obsessive-compulsive disorder (OCD) is characterized by repeated and persistent attempts to control thoughts and actions with rituals. These rituals are used in order to prevent feared or personally distressing outcomes. Cognitive behavioral group therapy (CBGT) has been reported to be effective for treating OCD patients. However, about one-third (30%) of patients do not benefit from CBGT. Some of these patients do not show significant improvement and continue to use rituals following CBGT, partially because they fail to complete the exposure and ritual prevention (ERP) exercises. Consequently, it is important to motivate patients to fully engage in CBGT treatment and complete the ERP exercises. Aims: A randomized behavioral trial examined 12 weeks of manual directed CBGT, with the addition of individual sessions of Motivational Interviewing (MI) and Thought Mapping (TM), and compared treatment outcome to the effectiveness of CBGT group alone. Method: Subjects were randomized (n = 93) into a CBGT group or a CBGT group with MI+TM. Results: When the two groups were compared, both groups reduced OCD symptoms. However, symptom reduction and remission were significantly higher in the MI+TM CBGT group. Positive outcomes were also maintained, with additional symptom reduction at the 3-month follow-up for the MI+TM CBGT group. Conclusions: Adding two individual sessions of MI and TM before CBGT successfully reduced OCD symptoms and was more effective than using CBGT group alone. Keywords: OCD, cognitive-behavioral group therapy, CBGT, Thought Mapping, Motivational Interviewing. Reprint requests to Elisabeth Meyer, Anxiety Disorders Program, Department of Psychiatry, Federal University of Rio Grande do Sul, Rua Ramiro Barcelos, 2350 Room 400N, 90035-903, Brazil. E-mail: meyer-beth@hotmail.com © British Association for Behavioural and Cognitive Psychotherapies 2010