The current study investigated the effects of an 8-week mindfulness-based substance use intervention on self-reported impulsiveness, perceived drug risk, and healthy self-regulation in a sample of 60 incarcerated youth. Forty-eight participants completed questionnaires pre and post intervention. Additionally, 16 participants from two of the final 8-week cohorts were interviewed in focus groups about their experience of the program immediately following its completion. A mixed-method embedded model was used, in which qualitative data was used in support of quantitative data. Paired t-tests revealed a significant decrease (p < .01) in impulsiveness and a significant increase (p < .05) in perceived risk of drug use from pretest to posttest. No significant differences were found on self-reported self-regulation. Focus group interviews conducted immediately following the intervention revealed three major themes: receptivity to the program in general, appreciation of the facilitator teaching style, and learning about drugs. Clinical implications and directions for future research are discussed.