The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) wishes to better understand the roles, structures and co-operation of drug demand reduction services in the health, social, educational and criminal justice sectors. As many have observed, there are a multiplicity of actors involved in addressing the problems of drugs and drug abuse. A careful examination of the different roles and structures each actor occupies can reveal the potential of the system for co-ordinated and therefore efficient action. More, an examination of the actual and potential co-operation amongst the actors can shed further light on the facilitators and barriers to achieving their potentials. In the European Union, with a diversity of drug policies and of relationships among the different actors engaged in drug policies, there exists a particular opportunity to learn from mutual experience.