Based on ethnographical studies of two « suburban » secondary schools, this paper aims at giving an account of how supervision and sanction mechanisms are built, showing that disciplinary policies concern all actors of secondary schools. Adult legitimacy regarding such issues is not only a question of status. Resources such as social or geographical origins, language and age closeness also matter. Unified policies are difficult to establish due to an unequal distribution of resources favouring, or not, adult legitimacy and division of roles. Under such conditions, students have resources to curb or even reverse a sanction or a norm imposed by adults.