This article provides a descriptive overview of the characteristics of a large metropolitan drug treatment system in relation to special populations of substance abusers enrolled in the system and the services provided. The findings are based on self-report responses to a comprehensive survey of 294 drug treatment programs in Los Angeles County. The special populations are grouped by health status, ethnic background, language needs, and gender-related needs. The groups are not mutually exclusive. Survey results indicated a generally high proportion of programs capable of meeting the unique needs of a variety of special population clients and most programs having some mix of special population clients in their current caseload. The types of services offered varied by modality and by special populations being served. Implications for program planning and service delivery include consideration of whether or not to offer specialized programs for unique client types.