This book explores nidotherapy: the systematic process of changing the physical, social, and personal environment for clients who have failed to respond fully to conventional treatments. Peter Tyrer argues that clients with personality disorders can improve enormously when placed in the right environment and introduces the process of nidotherapy. The chapters explore methods of matching the patient to the environment, modification of the environment, and patient adaptation, along with case examples and a glossary of key terms. Additionally, the use of ICD-11 classification to understand all aspects of a person’s personality is explored to assess personality difficulty, social prescribing, and treatments for severe personality disorder. This book is essential for psychiatrists, clinical psychologists and mental health professionals who treat personality disorders, as well as graduate students in clinical psychology courses.