Orthorexia nervosa (ON) is a putative eating disorder linked to perfectionism among people who eat healthily (or who want to eat healthily). However, little is known about the process by which perfectionism fosters ON symptoms. Like the Transdiagnostic Cognitive-Behavioral Theory of Eating Disorders, we hypothesized that perfectionism among people who eat healthily (or who want to eat healthily) fosters ON symptoms indirectly by cultivating a health-focused self-concept (i.e., placing overriding importance on health for self-definition and self-worth). We also hypothesized that a health-focused self-concept would be associated with ON symptoms among people who have erroneous beliefs about the safety and efficacy of maladaptive healthy eating strategies.