The key factors to be assessed include weight history, eating behavior, history of binge eating or purge behavior, diet history, overexercise patterns, body image, and, in females, menstrual history. Special assessment techniques for detecting eating disorders in athletes are described. The need for a detailed comprehensive case formulation incorporating factors that have predisposed, precipitated, and sustained the eating disorder is emphasized. Issues involved in choosing the type of treatment and site of treatment (inpatient, day patient, or outpatient) are discussed.