SummaryThe drug addict or ‘problem drug taker’ is the focus of a number of overlapping systems of regulation from moral to medical and penal. It is consequently difficult to analyse the development of policy in this area without lapsing into oversimplifications which imply either a process of medicalization or the unity of a totalitarian system of social control. It is argued here that we cannot adequately understand the development of policy in the field of drug addiction by reference to the medicalization of social problems and that a more fruitful course is opened up by analyzing developments of ‘rational knowledge’ which underpin policy shifts. In the light of this argument the apparent shifts in policy in the 1960s following the Second Brain Report are re‐