Part III provides brief descriptions of the most frequently used self-reported questionnaires (ORTO-15, Eating Habits Questionnaire, Düsseldorf Orthorexia Scale, Teruel Orthorexia Scale, Barcelona Orthorexia Scale, Orthorexia Nervosa Inventory, ORTO-R, Orthorexia Self-Test), to outline those that seem to be suitable as self-assessment tools to measure orthorexia nervosa and those that are promising in research and clinical settings. It also proposes Orthorexia Nervosa Screening Questions to detect the risk of orthorexia nervosa. A summation of the highlights is included at the end of this chapter. The commentary of the invited international expert (Dr Adrian Meule, the University Hospital of the LMU Munich and the Schoen Clinic Roseneck, Germany ) provides valuable insights on orthorexia nervosa.