Some of the unique characteristics of the drug abuse field which distinguish it from the other varieties of substance abuse and research methodologies for studying determinants of drug self-administration behavior which have been developed in response to these characteristics were investigated. Data suggest that residential drug self-administration laboratories are useful contexts for direct observation and measurement of drug self-administration behavior and assessment of experimentally manipulated environmental influences, and methadone maintenance treatment clinics provide settings for applied research on environmental determinants of drug self-administration. Results presented from a sequential group of studies in this setting indicate that contingent reinforcement procedures reduce supplementary drug self-administration by methadone patients. (Author)