This volume is the result of an EMCDDA-commissioned study carried out in 1998 and 1999 into one of the most widely discussed drug-related topics in Europe today: substitution treatment. The study was prompted by the lively debate on the issue in the mid-1990s, when Switzerland launched its first heroin trial, France began buprenorphine treatment and methadone programmes expanded rapidly throughout Europe. These initiatives led to an increased focus on substitution treatment and to the trajectories it was to follow in the future. The volume opens with a historical overview of substitution treatment, the development of methadone maintenance and other substitution services and a section on monitoring and evaluation. It closes with a series of country profiles for each of the then 15 EU Member States, all containing an introduction to substitution treatment in the country concerned.