This study explores factors associated with self-help group meeting attendance in the aftercare of 81 clients with dual diagnoses of severe mental illness and chemical dependency following their discharge from an inpatient chemical dependency treatment program. It also explores the association between self-help group meeting attendance and treatment outcomes. Data were collected from patient records and results of the Addiction Severity Index (ASI) administered as part of an earlier experiment that evaluated the effectiveness of the treatment program. Collaterals also provided follow-up information. Of thirteen variables examined, only two were associated with increased self-help group meeting attendance: having more years of education and having a major substance problem that did not include alcohol. No association was found between self-help group meeting attendance and treatment outcome regarding psychiatric problem severity or five other domains of the ASI. A moderate association was found indicating that more self-help group meeting attendance was related to improvements in the legal problems domain of the ASI. Implications are discussed for future research and for improving self-help group meeting attendance and its influence on treatment outcomes for individuals with dual diagnoses.