This chapter investigates the composition of prison gangs, their effects on the prison environment, and their relationships with street gangs. Through conducting an ethnographic study of an adult men's prison in England, the chapter attempts to articulate the experiences of prison gang members, as well as prisoners exposed to high levels of gang activity. The results illustrate the established role gangs play within English prisons, but also the relevance of other groups, collectives and “sets” within the penal environment. Through analysing the gathered data, I aim to show the important - but not defining - role gangs play within an English prison. Moreover, when compared to the American prison system, gangs are far less entrenched in English prisons; this can partly be attributed to the deeper historical roots of American prison gangs, as well as their highly racialized dimensions. The chapter begins with two case-studies, the subjects of which are prisoners from the research site.