Obsessive–compulsive disorder (OCD) and eating disorders (EDs) are highly comorbid. Despite the high comorbidity, there is little understanding of why these disorders coexist and even less research on how to best treat this co-occurrence. In this article, we review the literature on comorbid OCD-ED and discuss potential underlying shared mechanisms, including anxiety/avoidance, perfectionism, intolerance of uncertainty, habit formation, disgust, shame and guilt, rumination, metacognitive beliefs, and shared biological characteristics. We then discuss prior models of OCD-ED comorbidity and shift the perspective from latent or categorical models to dimensional symptom models (e.g., network models). We describe how dimensional symptom models could advance the conceptualization, treatment, and prevention of comorbid OCD-ED. Next, we discuss how idiographic (one-person) symptom models could advance personalized treatment and provide a treatment example. Finally, we discuss future research needed to advance the field and improve treatment outcomes.