Previous studies have identified phenotypic similarities between anorexia nervosa (AN) and body dysmorphic disorder (BDD), which share the common feature of negative body image. Studies comparing endophenotypes that may cut across both disorders-as suggested by the National Institute of Mental Health's Research Domain Criteria-are limited. Sixty-nine individuals (AN, n = 24; BDD, n = 23; mentally healthy controls [MHCs], n = 22) completed diagnostic interviews and self-reports assessing self-esteem and perfectionism. Clinical groups showed greater perfectionism in almost all subdimensions as well as poorer self-esteem compared with MHCs, with no clinical group differences when controlling for level of depression. Depression was a mediator of the relationship between symptom severity and self-esteem in both clinical groups. Comparable low self-esteem and greater perfectionism in AN and BDD corroborated existing etiological models and previous studies. Depression was a significant contributor to negative self-esteem in both disorders.