A variety of interventions, both therapeutic and preventive, have been used to control, reduce, or eliminate substance use and misuse and their attendant problems. Yet, despite years of ever more sophisticated and expensive ways of responding to the use and misuse of a variety of legal and illegal substances, addiction continues to be a major social problem for users, their families and communities, therapists and clinicians, policymakers, and the public. This paper examined both clinical treatment outcomes and broad-based population prevention interventions, and reviewed their underlying rationales. It identified a number of areas that must be addressed if the situation is to improve. These areas include a lack of agreement about what is meant by "addictions;" how effective interventions are to be defined and measured so that improved interventions can be implemented in the future; and the integration of the processes of quality and appropriateness into the planning, implementation, and assessment of substance-abuse interventions. A table outlines the evidence of effectiveness for various types of treatment for alcohol abuse. 1 figure, a glossary, and 19 references