Participants are adults or adolescents (16 year or older) who fulfill criteria for TTM according to DSM-IV. Inclusion started in January 2013 and will be completed by Mai 2016. Treatment is delivered at three treatment sites in Norway; in Kristiansand, Oslo, and Trondheim. Treatment is manualized, following the manual of Twohig and Woods, and consists of ten group sessions of three hours delivered at consecutive weeks, and two or three booster sessions during the first year after treatment.