Because eating disorders (EDs) and obsessive compulsive disorder (OCD) co-occur at high rates and can have functionally similar clinical presentations, it has been suggested that both constructs might be part of a common spectrum of disorders. Identifying the relationship between EDs and OCD may lead to the discovery of important shared core disease processes and/or mechanisms for maintenance. The objective of this paper is to understand the relationship between EDs and OCD by systematically reviewing epidemiological, longitudinal and family studies guided by five models of comorbidity posited by Klein and Riso (1993) and others. Though this literature is relatively small, the preponderance of evidence from these studies largely suggests that OCD/ED co-occur because of a shared etiological relationship. Limitations to extant literature, and suggestions for future research are discussed.