This chapter explores the activities and characteristics of street gangs and organised crime groups in contemporary British society. Although numerous studies exist which investigate youth delinquency and group violence in Britain, there is less research which specifically investigates contemporary British criminal gangs - carrying out such an exploration is the organizing principle of this chapter. Through conducting qualitative research at an adult men’s prison in England and its surrounding area, this chapter attempts to articulate the experiences of prisoners and street-offenders on this subject. The results illustrate the entrenched role street gangs and organised crime groups hold in certain areas of England; not only are they seen as viable alternatives to gainful employment, but their activities are often sanctioned by the communities within which they are based. Through an alternative set of social norms – not informing the police about criminal activities, being introduced to crime through family members, and aspiring to be involved in serious criminality – a symbiotic relationship exists between these communities and criminal gangs. Subsequently, a high level of violence is normalised within such communities, including heightened levels of weapon usage by gang members, both within and outside prison.