Abstract: The last two decades have witnessed an increase in the development of treatment guidelines in the European drugs field. This has largely built on a body of evidence on the treatment of drug dependence that has developed since the 1980s, alongside a growing interest in, and understanding of, the eff ectiveness of interventions. A range of tools became available to translate evidence into satisfactory and sustainable results, among them : guidelines and standards, education and training, implementation and assessment, monitoring, and accreditation systems based on quality standards. The focus of this Selected issue is drug dependence treatment guidelines – one of the main measures used to improve and guarantee the quality of drug treatment provision. The focus on drug dependence treatment is timely and appropriate, as current estimates suggest that at least 1.1 million people were treated for illicit drug use in the European Union, Croatia, Turkey and Norway during 2009 (1). This is the consequence of a major expansion of specialised outpatient services during the last twenty years, with the significant inclusion of primary healthcare, self-help groups, general mental health services, and outreach and low-threshold service providers. While more than half of clients received opioid substitution treatment, a substantial number received other forms of treatment for problems related to opioids, stimulants, cannabis and other illicit drugs. The main modalities used for the treatment of drug problems in Europe are opioid substitution, detoxification and psychosocial interventions. Drug dependence treatment services are provided in a variety of settings: specialised treatment units (including outpatient and inpatient centres), mental health clinics and hospitals, units in prison, lowthreshold agencies and by offi ce-based general practitioners. Particularly in western Europe, there appears to have been a gradual shift away from a view of drug dependence treatment as the responsibility of a few specialist disciplines providing intensive, short-term interventions towards a multidisciplinary, integrated and longer-term approach. Evidence suggests that continuous care and integrated treatment responses may be aided by the development and use of guidelines, care protocols and case management by all the relevant service providers (Haggerty et al., 2003). This publication sets out to introduce the topic of treatment quality improvement by the development of guidelines (and other documents), and to provide an overview of the existing national guidelines for the treatment of drug dependence in Europe.