An evidence-based treatment for adolescent cannabis users, Adolescent Community Reinforcement Approach with Assertive Continuing Care, was implemented in a rural county and small city in the USA. A total of 147 adolescents, ages 12-18, were enrolled and assessed at baseline and three time points: 3, 6, and 12 months using the Global Appraisal of Individual Needs and related measures. Program effectiveness was confirmed. The treatment was equally effective for youth from the city versus the county. More than two-thirds (68.7%) of the adolescents reported quitting use of cannabis by 12 months. The days of cannabis use in the last 90 days decreased significantly from the first follow-up, controlling for age (p value < .01), and shows consistent decline until the end of the treatment. In addition to reduction in substance use, the average number of days missing school and expelled from school decreased significantly from baseline to the end of the treatment.