PERIPHERAL URBAN AREAS AND STATE INTERVENTION IN MEXICO CITY This study is based on surveys carried out in eighteen working-class suburbs on the outskirts of Mexico City. Two main topics were covered : firstly, the strategies of agents who intervened in the processes of land acquisition and allocation, and property régularisation, and secondly, the forms of organisation of social groups and their relationship with the state. Two types of agent can be identified, according to the type of land ownership and their role is a determining one. The first group are developers who are building on state and private land, and the second are the ejido commissioners who intervene in ejido and communal land. Although relations between occupants and developers vary according to cases, explicit intervention (regularization) and implicit intervention (tolerance) by the authorities is relevant in both cases. An analysis of the nature, role and logics of state intervention provides an understanding of the issues at stake in the question of urban land and its function as a means of regulating social relation. The state's apparent laissez-faire policy masks indirect intervention with which it is aiming to establish organisational formations based on community relationships or managed by state-appointed organizations, and thus avoid an independent mobilisation of the working-classes. It would seem that relations between the state and the masses constitute the main decisive, variable factor in the study of social formations in all the surburbs on the outskirts of Mexico City.