This book aims to explore the evidence supporting the therapeutic community (TC) modality as a uniquely effective approach to care of individuals living with opioid use disorder and other addictions, and also to identify salient mediators of improved outcome, including long-term treatment and removal from the opioid-associated environment. The book includes multiple international perspectives and is designed for worldwide appeal―for countries that have established some TCs with success, those looking to improve care, and those looking to build them for the first time.