Eating disorders (EDs) are a group of prevalent psychiatric illnesses with an onset in early to late adolescence-a time of significant neural development, physical and psychologic growth, and self-exploration. The etiology and neurobiology of EDs are not well understood, but EDs are recognized as brain-based illnesses with serious acute and long-term consequences if undertreated or ignored. Two EDs, anorexia nervosa (AN) and bulimia nervosa (BN), have historically been the primary EDs of focus. The DSM-5 updated diagnostic criteria for these disorders added two more: binge-eating disorder (BED) and avoidant/restrictive food intake disorder (ARFID). EDs severely impact males as well as females across the weight spectrum. Comorbidity is high; mortality rates for AN and BN are the highest in psychiatric conditions and higher than many medical conditions. Several treatment options are available to treat an ED ranging from inpatient hospitalization to outpatient services and different psychotherapy options. This chapter reviews the diagnostic criteria, clinical presentation, and treatment for these disorders. Where available, sex differences and developmental considerations will be noted. For all EDs, early recognition and swift treatment are necessary to avoid a chronic course.