A heterogeneous and representative sample of 323 homeless individuals in the metropolitan-Denver area with alcohol or other substance abuse problems received a comprehensive array of substance-abuse treatment services. Following treatment, these individuals showed dramatic improvement on average in their (a) levels of alcohol and drug use, (b) housing status, (c) physical and mental health, (d) employment, and (e) quality of life. Those who received more service improved more than those who received less service. These improvements are attributable, at least partly, to the treatment rather than to alternative hypotheses such as spontaneous remission. However, the rate of improvement generally slowed during the six-month follow-up period. A random half of the clients received intensive case management in addition to the other services. Case management marginally increased clients' contacts with addictions counselors, but had little effect on the level of other services received or on the tailoring of services to client needs. As a result, case management also had little, if any, effect on outcomes.