However much policy material is produced, the real function of most child psychiatrists is to assess and treat mental disorders in childhood and adolescence. This is a comprehensive update on the field that will inform the clinical practice of all child and adolescent mental health professionals. The authors bring the medical perspective to bear on psychopathology and demonstrate that our understanding of childhood psychiatric disorders, their origins and their treatments are improving. They write with a particular focus on four contemporary themes – continuity into adult life, the integration of biological and social aetiology, the influence of neuroscience, and the increasing use of research and evidence – and take into account recent changes in DSM-5. Some chapters have been specially commissioned for this book, while previous versions of the others have been published in the journal Advences in Psychiatric Treatment and have now been fully revised and updated in line with the four themes. The new chapters include disorders in 0- to 4-year-olds, Tourette syndrome and the clinically significant topic of anxiety. Other topics include: autism spectrum disorders, behavioural and affective disorders, pharmacology and psychological therapies, fabrication and induction of illness, and gender dysphoria. All the topics covered are central to the work of practising child and adolescent mental health professionals, and many will also be relevant to paediatricians, psychologists, social workers, and trainees in all these fields.