The purpose of this study was to examine the history of arrests among dually diagnosed patients entering treatment, compare groups with different histories on use of treatment and mutual-help groups and functioning, at intake to treatment and six-month, one-year, and two-year follow-ups, and examine correlates and predictors of legal functioning at the study endpoint. At treatment intake, 9.2% of patients had no arrest history, 56.3% had been arrested for nonviolent offenses only, and 34.5% had been arrested for violent offenses. At baseline, the violent group had used the most outpatient psychiatric treatment and reported poorer functioning (psychiatric, alcohol, drug, employment, and family/social). Both arrest groups had used more inpatient/residential treatment and had more mutual-help group participation than the no-arrest group. The arrest groups had higher likelihood of substance use disorder treatment or mutual-help group participation at follow-ups. Generally, all groups were comparable on functioning at follow-ups (with baseline functioning controlled). With baseline arrest status controlled, earlier predictors of more severe legal problems at the two-year follow-up were more severe psychological, family/social, and drug problems. Findings suggest that dually diagnosed patients with a history of arrests for violent offenses may achieve comparable treatment outcomes to those of patients with milder criminal histories.