 Over a period of 3 weeks, association splitting is compared to cognitive remediation CogPack training as an add-on intervention to cognitive-behavioral therapy CBT. Blind to treatment assignment, both groups are assessed before intervention and eight weeks as well as six months later with the Yale-Brown Obsessive Compulsive Scale Y-BOCS, the Obsessive-Compulsive Inventory OCI-R and cognitive tests. OCD severity as measured by the Y-BOCS total score serves as the primary outcome parameter. It is assumed that association splitting will improve OCD severity to a greater extent than cognitive remediation. 