Based upon two years of ethnographic fieldwork in London, England, which incorporated nearly 200 interviews with gang members, gang associates, and police officers, among others, this thesis addresses three questions presently unresolved in the street gangs literature: What is the business of gangs? How are gangs organised? And how do gangs recruit? With regard the business of gangs, this thesis illustrates how recreation, crime, enterprise, and extra-legal governance represent sequential stages in the evolutionary cycle of London’s street gangs. Gang member testimony emphasises how gangs typically begin life as neighbourhood-based peer groups, but also how, in response to external threats and financial commitments, gangs grow to incorporate street-level drugs distribution businesses that very much resemble the multi-level marketing structure of direct-sales companies. People join gangs to make money, achieve status, and obtain protection. Gangs engage in turf wars, acquire violent resources, and develop hierarchical structures in order to maintain provision of these desirable goods and services. Gang organisation, in turn, becomes a function of gang business. To better understand the nature and extent of gang organisation, this thesis moves on to discuss the presence of subgroups, hierarchy and leadership, pecuniary and non-pecuniary incentives, rules, responsibilities, and restrictions, and consequences for absconding within gangs. It further presents how, in order to convey reputation and achieve intimidation, gangs seek association with elements of popular culture that help promote their image. Finally, through the novel application of signalling theory to the gang recruitment process, this thesis demonstrates how gangs face a primary trust dilemma in their uncertainty over the quality of recruits. Given that none of the trust-warranting properties for gang membership can be readily discovered from observation, gangs look for observable signs correlated with these properties. Gangs face a secondary trust dilemma in their uncertainty over the reliability of signs because certain agents (e.g., police informants, rival gang members, and adventure-seekers) have incentives to mimic them. To overcome their informational asymmetry gangs thus screen for signs that are too costly for mimics to fake but affordable for the genuine article. The thesis concludes with a discussion of gang desistance and intervention in the context of escalating youth violence in London.

La tradition criminologique conçoit volontiers le crime comme un fait individuel. A rebours de cette conception, cette thèse se propose de comprendre le crime comme un fait social et politique. Les modèles matérialistes et culturalistes classiques ont pu rendre compte des variables économiques et culturelles explicatives du crime. Pour autant, ils ont insuffisamment pris en compte ce fait fondamental que l’activité criminelle est, dans sa masse, une activité de groupe. En particulier, ils peinent à expliquer la surreprésentation des minorités -notamment ethniques- dans le crime. Un modèle sociométrique dit d’ « encastrement criminel » permet de montrer en quoi la sociabilité des minorités donne des avantages comparatifs auxdites minorités dans la criminalité organisée.Parce qu’elle est d’abord un phénomène de réseaux, la criminalité s’explique donc en comprenant les logiques économiques qui motivent les membres des réseaux criminels, mais également les logiques ethno-culturelles qui les structurent. De telles logiques sont toujours prédominantes dans le monde contemporain, marqué par la globalisation, le caractère plus virtuel des échanges, le communautarisme et le terrorisme. Ces logiques économiques et culturelles ont insuffisamment été prises en compte par les politiques publiques de sécurité en France, en particulier les politiques de la ville et de renseignement criminel. Cela tient en bonne partie au modèle français, qui peine à appréhender les logiques du crime de façon pragmatique, et à prendre en compte l’ethnicité. / Criminal networks between economic and cultural logics The criminological tradition readily conceives crime as an individual fact. Unlike this conception, this thesis proposes to understand the crime as a social and political fact. The traditional materialistic and culturalist models were able to account for the explanatory economic and cultural variables of the crime. However, they have insufficiently taken into account this fundamental fact that criminal activity is, in its mass, a group activity. In particular, they are struggling to explain the over-representation of minorities-especially ethnic-in crime. A sociometric model called "Criminal embeddedness" shows how the sociability of minorities gives comparative advantages to such minorities in organized crime.Because it is primarily a phenomenon of networks, crime is thus explained by understanding the economic logics that motivate members of criminal networks, but also the ethno-cultural logics that structure them. Such logics are always prevalent in the contemporary world, characterized by globalization, the more virtual nature of trade, communitarianism and terrorism. These economic and cultural logics were not sufficiently taken into account by public security policies in France, in particular in urban governance and in criminal intelligence policies. This is largely due to the French model, which is struggling to grasp the logic of crime in a pragmatic way, and to take into account ethnicity.