Although the Minnesota Model of treatment for alcohol and drug addiction is a common treatment approach, there are few published reports of its effectiveness. This study describes the Minnesota Model treatment approach as practiced at Hazelden, a private residential alcohol and drug abuse treatment center located in Center City, Minnesota (a founding program of the Minnesota Model) and presents recent outcome results from this program. This study includes 1,083 male and female clients admitted to Hazelden for treatment of a psychoactive substance-use disorder between 1989 and 1991. The outcome study is a one group pretest/posttest design. Data collection occurred at admission to treatment and at 1-month, 6-month, and 12-month posttreatment. At 1-year follow-up, 53% reported that they remained abstinent during the year following treatment and an additional 35% had reduced their alcohol and drug use. These results are similar to those reported by other private treatment programs. The Minnesota Model has consistently yielded satisfactory outcome results, and future research needs to focus on the therapeutic process of this common treatment approach.