Since first developed by Dole and Nyswander, there have been significant changes in the clinical use of methadone, based on evaluation of the initial programs and a better understanding of the psychology and pharmacology of addictive behavior. Treatment has evolved from Dole's original concept that methadone "blockaded" the euphoric effect of heroin to current usage which reflects a greater appreciation of methadone's ability to prevent the development of withdrawal symptoms and to moderate intense affective states. The successes and limitations of methadone maintenance are best appreciated in comparison with alternative treatment modalities including therapeutic communities and detoxification. Program administrators face unique pressures because of the need to resolve the often contradictory goals of patients, staff, community groups, law enforcement officials, government regulators and funding agents. The evolution of effective treatment models has been greatly impaired by these pressures. Clinicians must become more effective leaders in helping to resolve these problems and to help formulate more rational drug abuse treatment policy.