This chapter focuses on conditions characterized by severe disturbances in eating behavior that are grouped within the category of ‘‘eating disorders’’ in the Diagnostic and Statistical Manual, 4th edn. . This reference text, popularly known as the DSM-IV, had a ‘‘text revision’’ in 2000, but there were no changes for eating disorder criteria. The purpose of the DSM-IV is to deﬁne diagnostic categories for clinicians and researchers to treat and study individuals with ‘‘mental disorders,’’ a poorly deﬁned term applied to conditions that have prominent emotional, behavioral, and psychological symptoms. Although evidence points toward a strong biological component to the initiation and maintenance of eating disorders, with emerging evidence of a genetic predisposition that may be triggered by developmental and environmental factors, eating disorders are still considered ‘‘psychiatric’’ conditions by many professionals, resulting in many limitations to both treatment and research beyond the scope of this chapter.