Drug addiction is a complex illness, and not all drug abuse treat. is equally effective. Research also has revealed a set of principles that characterize the most effective drug abuse and addiction treat. and their implementation. To share the results of this extensive body of research and foster more widespread use of scientifically based treat. components, the Nat. Conf. on Drug Addiction Treatment was held in 1998. This guide: summarizes basic principles that characterize effective treat.; provides answers to frequently raised questions about these principles; describes the types of treat.; and presents examples of scientifically based and tested treat. components.