The Drug Enforcement Administration (DEA) administers and enforces the Controlled Substances Act (CSA) as it pertains to ensuring the availability of controlled substances, including certain prescription drugs, for legitimate use while limiting their availability for abuse and diversion. The CSA requires those handling controlled substances to register with DEA. This book examines to what extent registrants interact with DEA about their CSA responsibilities, and registrants’ perspectives on those interactions; how state agencies and national associations interact with DEA, and their perspectives on those interactions; and stakeholders’ perspectives on how DEA enforcement actions have affected prescription drug abuse and diversion and access to those drugs for legitimate needs. The book also highlights certain non-criminal regulatory requirements.