Obsessive-compulsive disorder (OCD) is one of the most disabling and highly prevalent anxiety disorders. Cognitive models implicate maladaptive beliefs such as inflated sense of responsibility, perfectionism, importance/control of thoughts in the maintenance of the disorder, but little research has investigated factors that may lead to these beliefs. This paper investigated whether a dysfunctional attachment system may be one such factor, by examining how adult attachment orientations (dimensions of attachment anxiety and avoidance) relate to OCD-related cognitions, OCD symptoms, and depression. Using structural equation modeling in a student sample (N = 446), the present study found evidence for a mediational model, where attachment dimensions contributed to OCD symptoms via OCD-related cognitions, while controlling for depression. The paper discusses the association between adult attachment orientations and OCD symptoms in the context of current cognitive-behavioral theories of OCD.