The aims of this exploratory pilot study were to examine how a substance use disorder (SUD) treatment program for young adult males integrated mindfulness-based experiences into the treatment process, and to assess the impact of these experiences on the development of mindfulness skills and treatment outcome. The study utilized a within-subject naturalistic mixed-method design that integrated quantitative and qualitative data where all participants who entered treatment and agreed to participate in the evaluation were included in the data collection. A total of 32 young men were included in the analysis with an average age of 22.9 years. Statistically significant changes in scores on the Five Facet Mindfulness Questionnaire (FFMQ) from pre- to post-treatment were noted for all clients as a result of treatment, and these changes were strongly correlated to treatment outcome as indicated by statistically significant changes in total OQ-45.2 scores. Clients also showed specific improvement in scores on mindfulness skills related to the nonjudging and nonreactivity facets of the FFMQ which were related to reductions in the client’s overall subjective distress as measured by the OQ-45.2. Qualitative findings from analysis of client comments support these findings and highlight client perspective of the value of mindfulness-based experiences in addictions treatment. Despite the limitations inherent in this exploratory study, mindfulness-based experiences (MBEs) are discussed as a promising approach in the treatment of SUD and suggest further research in this area of addiction treatment.