Twelve-step groups have been evaluated as effective recovery resources for alcoholics. Many substance abusers also have a comorbid mental health disorder, leading to greater treatment challenges and poorer treatment outcomes. Moreover, despite their effectiveness, 12-step programs are underutilized by dually-diagnosed persons. In order to gain a better understanding of participation in both traditional and dual-focus 12-step treatment programs, the authors followed 277 members of a dual-focus 12-step program over 1 year, collecting semi-structured questionnaire data. Among the variables examined were reasons for attending the program, perceived benefits of affiliation, perceived obstacles to affiliation, and predictors of affiliation. Results of statistical analyses revealed dually-diagnosed persons expressed differing comfort levels with 12-step programs, although many did engage in both types of programs (traditional and dual-focus). Both types of programs were identified as useful for the subjects. Greater difficulty with substance use at baseline was predictive of greater attendance of 12-step programs at follow-up. Limitations of the study include problems of generalizability. The authors suggest that their findings indicate that dually-diagnosed persons should be encouraged to participate in dual-focus 12-step programs if they are available. However, affiliation with traditional 12-step programs is also useful for dually-diagnosed persons and should be encouraged where no dual-focus program is available. Tables, references