This study was a cross-cultural replication of a study that investigated therapist adherence to behavioral interventions as a result of an intensive quality assurance system which was integrated into Multisystemic Therapy (MST). Thirty-three therapists and eight supervisors were block randomized to either an Intensive Quality Assurance or a Workshop Only condition. Twenty-one of these therapists treated 41 cannabis-abusing adolescents and their families. Therapist adherence and youth drug screens were collected during a 5-month baseline period prior to the workshop on contingency management and during 12 months post workshop. The results replicated the previous finding that intensive quality assurance enhanced therapist adherence over workshop, to cognitive-behavioral techniques, but not to contingency management. While the clinical impact of such quality assurance remains to be demonstrated, cannabis abstinence increased as a function of time in therapy, and was more likely with stronger adherence to contingency management, but did not differ across quality assurance interventions. (Contains 1 figure and 4 tables.)