Analysis of the interactions at the heart of deviant careers is placed alongside that of the social logic which produces a favorable climate for the diffusion and expansion of the drug economy in poor areas. Using criminal records and interviews about careers from a study in the metropolitan area of Lille and in two communes of Hauts-de-Seine, France, the article examines two particular aspects: the characteristics of user careers and those of trafficking careers. The results underline the fact that the drug economy is not simply a means to 'turn off' in the face of poverty, but that it also includes social and symbolic dimensions which are closely linked to the particular urban contexts studied. 48 references and 9 footnotes