Obsessive-compulsive disorder (OCD) is associated with an inflated sense of responsibility to prevent harm. Increasingly, it has been recognized that inflated responsibility is a complex phenomenon. The purpose of this study was to examine how interpersonal aspects of responsibility are related to symptoms of OCD. Three new valid and reliable scales assessing beliefs about other people's responsibility, comparative beliefs about responsibility, beliefs about the allocation of responsibility, and beliefs about how others allocate responsibility were used to evaluate interpersonal influences on responsibility. Whereas personal beliefs about responsibility were related to all OCD symptom types, it appears that beliefs about other people's responsibility were related to only a subgroup of symptom types. Furthermore, the belief that one is more responsible than others predicts OC symptoms beyond commonly assessed personal beliefs about responsibility. Finally, individuals with OC symptoms tend to allocate more responsibility to themselves than others, compared to individuals without OC symptoms, despite the fact that individuals with OC symptoms believe that others tend to allocate responsibility equitably. Results are discussed in terms of cognitive models of OCD.