dependence and, second, to inform about prevention, harm minimiza- tion, treatment and control, in order that professionals can identify, assess and work with different kinds of drug misusers. It also aims to give information about the wide range of multidisciplinary and special- ist professionals who can contribute in this field. BACKGROUND The ancient Greek word for drug has three meanings: a cure or remedy, a poison and a magical charm. This book will consider these meanings in the modern sense: drugs as medication and as a solution to problems; drugs as dangerous to health; and drugs as magical and hedonistic. In the recent past, policy and practice guidelines have often been based on a misunderstanding of the diversity and complexity of drug misuse. Professionals have confused different types of drug misuse and/ or attempted to compress all types into one narrowly defined cate- gory, i.e. all drugs are good or bad. This is the first mistake: it is prefer- able to go right back to the ancient Greeks and try to understand the range of different effects of drugs on different people. Practitioners first of all need to understand the complexity of drug misuse in order to develop realistic concepts and construct useful cate- gories for assessment. After this, they are in a position to identify clearly the main risks and problems in the different categories and so to deter- mine which type of intervention is most appropriate.