This study examines variables that could predict treatment perseverance and impact for offenders (N = 124) admitted to one of five rehabilitation centers for alcoholics/drug addicts representing different regions of the province of Quebec. Information was collected on time spent in treatment, alcohol/drug use-related problems, motivation to change, criminal profile, subject's perception of judicial pressure, subjective assessment of importance/probability of judicial consequences tied to treatment dropout or substance use, quality of the therapeutic relationship, assessment of client commitment to treatment, and social support. Results indicate that judicial pressure only have impact on retention into treatment for those who are not already sentenced but this "forced" retention is not linked with positive results. The study's limitations are noted.