This paper describes psychosocial outcomes of an Indigenous residential substance abuse rehabilitation centre in Australia, examines the sensitivity to change of the new Growth and Empowerment Measure (GEM), and explores the degree to which service users value cultural components of the treatment program. Participants were 57 Indigenous and 46 non-Indigenous male clients from Oolong House. Intake, 8-weeks, and 16-weeks (program completion) measures of Kessler 10 Psychological Distress Scale (K10), Drug Taking Confidence Questionnaire (DTCQ-8), and GEM were completed. The Treatment Component Evaluation (TCE) was completed at 16-weeks. There were significant improvements for participants, with a decrease in psychological distress and increases in refusal self-efficacy and empowerment. Effect sizes for GEM were medium to large across the time-points (r = 0. 61 to 0. 70 for all four subscales from baseline to 8-weeks; r = 0. 44 to 0. 70 for three subscales from 8-weeks to 16-weeks), indicating sensitivity to change. Indigenous participants rated cultural components of treatment significantly more helpful than did non-Indigenous participants. Implications for future research and substance abuse interventions for Indigenous Australians are discussed.