The purpose of the CYT Project was to test the relative effectiveness and cost-effectiveness of a variety of interventions designed to eliminate marijuana use and associated problems in adolescents while providing validated models of these interventions to the treatment field. The target population was adolescents with cannabis-use disorders of abuse or dependence, as defined by the American Psychiatric Association (1994), who were assessed as appropriate for treatment in outpatient settings. The MDFT approach involves a multisystemic family-focused treatment conducted by experienced family therapists. It includes 12 weeks of in-clinic and telephone sessions with individual adolescents and their families. MDFT targets the psychosocial functioning of individual family members, the family members' relationships, and influential social systems outside the family. This volume details the MDFT approach to cannabis treatment; the operational features of the MDFT sessions; the goals, rationale, and procedures of MDFT interventions; the interdependence of emotions and cognitions in MDFT; procedural steps in implementing MDFT (facilitating key therapeutic processes); and guidelines for subsystem sessions. 320 references and appended supplementary material, including a review of evaluation outcomes for MDFT and administrative issues in implementing MDFT in CYT