Athletes are always aiming to be faster, better, stronger. New techniques to enhance their sporting performance have increasingly been linked to use of novel psychoactive substances (NPS) and other hard-to-detect substances like performance-enhancing drugs. This book offers a timely analysis of the new challenges posed by this phenomenon in the anti-doping community. The authors present the first comprehensive perspective on the rapidly shifting doping scenario and reflect on use, regulation, policy, and market structure of NPS used in sports. They highlight the challenges with the list of prohibited substances and methods in and out of competition. They also evaluate how methods to detect new drugs present an ongoing battle for doping control as they have to be adapted constantly. Topics covered within the chapters include: Contamination of Sports Supplements with Novel Psychoactive Substances; Untested Supplement Use Among Athletes: An Overlooked Phenomenon?; International Drug Control: Protecting the Health of the Athlete; and Analysis of New Chemical Entities in a Sport Context. This book establishes a clear benchmark on the policy discussion, drawing from available evidence and sources, including athletes' personal experiences, to generate a fact-based resource that informs a research as well as wider audience. The book is essential reading for those working in anti-doping, substance misuse, sports, ethics, and human enhancement. It also is useful for policymakers, legislative personnel, and other professionals with an interest in protecting clean sport.