Book excerpt: Harm Reduction is a philosophy of public health intended as a progressive alternative to the prohibition of certain potentially dangerous lifestyle choices. Recognising that certain people always have and always will engage in behaviours which carry risks, the aim of harm reduction is to mitigate the potential dangers and health risks associated with those behaviours. Harm Reduction in Substance Use and High-Risk Behaviour offers a comprehensive exploration of the policy, practice and evidence base of harm reduction. Starting with a history of harm reduction, the book addresses key ethical and legal issues central to the debates and developments in the field. It discusses the full range of psychoactive substances, behaviours and communities with chapters on injecting, dance drugs, stimulant use, tobacco harm reduction, alcohol use and sex work. Written by an international team of contributors, this text provides an essential panorama of harm reduction in the 21st century for educators and researchers in addiction and public health, postgraduate students and policy makers.