A number of articles consider how treatment program outcomes should be defined. One article reviews the rise of evidence-based medicine as the primary criterion of quality and describes the most common models for characterizing drug dependence and its treatment. Another article describes a wide range of performance measures that are relevant to substance dependency treatment programs. Another group of articles considers how research-based quality treatment can be disseminated to the field. Using the example of alcoholism treatment, one article shows that the underlying assumptions of the influential Minnesota model have garnered little empirical support, while more promising alternative treatment models have not been widely implemented. Ways of improving collaboration between researchers and practitioners are discussed. Three articles consider the role of accreditation models in promoting treatment quality, as they detail new accreditation models for substance dependency programs. Three articles discuss the conceptualization and measurement of treatment processes. Among the topics addressed in these articles are a multilevel framework for treatment process studies, the development of an Addiction Treatment Inventory, and a structured instrument intended to measure the diversity of therapeutic community programs. Two articles focus on guidance about program/treatment quality from the research base, with attention to the Services Research Outcome Study, the first effectiveness study based on a nationally representative sample of drug dependency treatment programs, with clients studied over an extended time period. References accompany the articles.