The aim of this book is to collate what is known about an array of complicating factors for patients with eating disorders, serving as an accessible introduction to each of the comorbidities and symptom presentations highlighted in the volume. The Handbook of Complex and Atypical Eating Disorders presents the available data about atypical and complex ED, in addition to what is known about treatment approaches. The first section contains chapters on the treatment of eating disorders with various psychiatric comorbidities, including trauma, borderline personality disorder, substance use, suicidality, anxiety disorders, and autism spectrum disorders, which may greatly complicate the application of standard treatment approaches. The second section contains chapters exploring treatment of eating disorders with atypical symptom presentations which (i) are not located as a specific diagnostic category in diagnostic criteria for ED’s, (ii) centrally feature ED pathology, and (iii) have emerging data suggesting the distinct nature of the syndrome, including purging disorder, muscle dysmorphia, night eating syndrome, and anorexia with a history of obesity. The final section has chapters which focus on how to adapt eating disorder treatment for atypical populations typically neglected in controlled treatment trials: LGBT, pediatric, male, ethnically diverse, and older adults.