In this study the researchers set up a clinical trial to examine the effects of 12 step program for individuals with mental illness and drug and alcohol dependence. In this experimental design they randomly assigned participants to either a 12-step facilitation therapy (TFS) or to treatment as usual (TAU) in an outpatient dual diagnosis program. Participants were assessed every four weeks in the 12 weeks of treatment, and every 12 weeks for 36 weeks after the treatment. Substance use and consequences were measured through surveys, such as, Form 90-A, A Time-line-follow-back (TLFB) questionnaire and The Short Inventory of Problems (SIP). Blood alcohol concentration (BAC), urine drug screening were also used to measure substance use. Psychiatric
