This article examines the control practices used in drug treatment services to regulate the behaviour of people with drug problems. Drawing on an extensive qualitative study, we developed a conceptual framework, integrating the notion of responsive regulation with Wrong’s sociology of power. The picture that emerges is of a complex ‘web of controls’, combining diverse forms of power and control techniques, used to steer action and shape behavioural outcomes. It is argued that we can understand these control practices within drug treatment as part of broader strategies for the social regulation of the poor, built on deep-rooted hybrids of punishment and welfare. The article concludes with the suggestion that drug treatment represents an important site for understanding penal power today.