Prison violence has always been a prescient problem, but the scale and severity of that problem increased in English and Welsh prisons during the 2010s and into the 2020s. The responsibility for this increase was attributed to young, drug-using, and gang-affiliated men. Not only do these explanations lack validity, but they also overlook the significance and impact of social, cultural, economic, policy, and technological change within prisons in England and Wales. Crucially, it is the moral quality of prison life that has declined and that serves as the principal explanatory factor. This book draws on immersive ethnographic and qualitative research to explore the nature, culture, dynamics, and causes of prison violence and victimisation among young adult men (aged 18–21 years old). This introductory chapter critically analyses the existing scholarship on prison violence and sets out why ethnographic and qualitative research is needed when seeking to understand illicit behaviour.