Homeless people with alcohol and other drug problems present the traditional substance abuse services delivery provider with special challenges. This paper discusses the optimal designs of comprehensive treatment services for homeless persons with alcohol and other drug problems. Most importantly, the homeless must have immediate access to a safe setting where they may at least temporarily reside. Providers must then place the client in the appropriate level of care in the continuum of services. Likewise, through intensive case management or other service, the provider must address the multiple needs of the homeless, including health and dental care, mental health treatment, vocational training, and benefits acquisition. In many cases, improvement in daily living skills will help the client attain a higher level of functioning. Services must be delivered consistently over a lengthy span of time since many individuals in this target population exhibit chronic substance abuse problems. Finally, service providers should recognize that full recovery may never occur; improvement in the level of functioning, in health status, and in the number of days intoxicated are more realistic goals for many of these clients than is a lifetime of sobriety. Contains nine references. (RJM)