This thesis investigates the practices and compositions of gangs in Greater Manchester, England. Primarily drawing from qualitative data gathered in two adult, men’s prisons, it explores gang members’ activities, how these practices develop on ‘the street’, and how they are later affected by imprisonment. The thesis also explores the links between race, geographical area and gang affiliation, analysing how a gang member’s racial background and area of origin may relate to his gang. The results show the strong influence of gangs at the sample prisons, and how gangs affect the ways in which prisoners negotiate the carceral space: violent practices, gang allegiances and rivalries developed on ‘the street’ are regularly transplanted into prison. These high levels of gang ‘importation’ into the sample prisons result in the social and cultural significance of street gangs often penetrating prison walls. Area of origin and shared racial background are strong unifying ‘banners’ under which many prison gangs operate, and violence is an integral part of life in ‘the gang’. However, reflecting the academic literature, gang members often contest the terminology around ‘gangs’, showing the polarized discourse around these topics. The thesis attempts to resolve some of these debates by presenting a comprehensive gang typology shaped by theory and prisoners’ testimonies.