The study goal was to determine whether client attributes were associated with outcomes from group cognitive behavioral therapy for depression (GCBT-D) as delivered in community-based addiction treatment settings. Data from 299 depressed residential clients assigned to receive either usual care (N = 159) or usual care plus GCBT-D (N = 140) were examined. Potential moderators included gender, race/ethnicity, education, referral status, and problem substance use. Study outcomes at 6 months post-baseline included changes in depressive symptoms, mental health functioning, negative consequences from substance use, and percentage of days abstinent. Initial examination indicated that non-Hispanic Whites had significantly better outcomes than other racial/ethnic groups on two of the four outcomes. After correcting for multiple testing, none of the examined client attributes moderated the treatment effect. GCBT-D appears effective; however, the magnitude and consistency of treatment effects indicate that it may be less helpful among members of racial/ethnic minority groups and is worthy of future study.